I think the GNU response is more subtle than "boycott it". In particular, I do not get the impression that GNU opposes someone using software that runs on someone else's server machine in general. One obvious example would be an HTTP server with PHP scripts, or whatever.
The software running on the remote server could even be proprietary software! For the sake of the person running the server, they should not use proprietary software, but if it is running on their machine and not yours, then it is not your responsibility, and (as I understand the GNU position) not wrong for you to access that software.
Now, if the software is actually a combination of server-side software and client-side software, such as servers that deliver Javascript code to be run locally, then that Javascript software should be Free Software.
But moreover, the GNU concern about running software on remote servers (i.e., "in the cloud"), is not just about the software itself, but about what the server maintainers can and do do with user data. Who owns the data? Can you get a copy of it? Can you get a copy of _all_ of it? How about the implications of the data? For example, you could tell Facebook ten things about yourself, and they could extrapolate a hundred more. Is "your data" the ten things only, and not the additional hundred extrapolations? And, if you ask them to delete "your data", will they? If they do, what exactly do they delete?
So it's really more of a privacy issue, I think, than a pure "free software" issue, but important nevertheless.
> The software running on the remote server could even be proprietary software! For the sake of the person running the server, they should not use proprietary software, but if it is running on their machine and not yours, then it is not your responsibility, and (as I understand the GNU position) not wrong for you to access that software.
I'd expect them to prefer you to use free software on the server, licensed under the AGPL.
I thought I had read something along those lines in a GNU document, but I believe I found what I was thinking of on Stallman's personal web site:
I firmly refuse to install non-free software or tolerate its installed presence on my computer or on computers set up for me.
However, if I am visiting somewhere and the machines available nearby happen to contain non-free software, through no doing of mine, I don't refuse to touch them. I will use them briefly for tasks such as browsing. This limited usage doesn't give my assent to the software's license, or make me responsible its being present in the computer, or make me the possessor of a copy of it, so I don't see an ethical obligation to refrain from this. Of course, I explain to the local people why they should migrate the machines to free software, but I don't push them hard, because annoying them is not the way to convince them.
Likewise, I don't need to worry about what software is in a kiosk, pay phone, or ATM that I am using. I hope their owners migrate them to free software, for their sake, but there's no need for me to refuse to touch them until then. (I do consider what those machines and their owners might do with my personal data, but that's a different issue, which would arise just the same even if they did use free software. My response to that issue is to minimize those activities which give them any data about me.)
A kiosk, pay phone, ATM, or someone else's personal computer is indeed not a "cloud" server; I might reasonably extrapolate that Stallman would have the same opinion about software installed on someone else's server, but whether if that is true or not, this may in fact not be an official "GNU" position, as such.
> I do not get the impression that GNU opposes someone using software that runs on someone else's server machine in general.
That's my impression as well, but to me that is an area where the FSF/GNU/RMS is fundamentally wrong. Not having control over the software and, even more important, the data that is on the server is the main reason why everything is going to shit. Yet the FSF doesn't seem to care, specifically this reply from RMS on the topic:
All the privacy, censorship and other problems with Facebook, Youtube, smartphones and so on are rooted in somebody else controlling the server, and in turn the software and the data.
If the Javascript is GPL or not is essentially irrelevant, yet that is the main problem the FSF focuses on. I can understand how the FSF would came to that conclusion (by following their philosophy that has been outdated for decades), but it completely misses all the problems people have day to day on the Internet.
How data is managed and controlled on the server should be the main concern of the FSF today, but there has been shockingly little effort in that area. I am not even talking in terms of actual software solutions, but just general philosophy discussions. The few bits of effort we have seen, such as the AGPL, not only don't go anywhere far enough, it wasn't even originally created by the FSF. And their repo-criteria completely miss the point.
Ironically, even the slow moving field of politics went to overtake the FSF here. The GDPR goes far and beyond anything I have ever seen by the FSF when it comes to data freedom.
I really wish the FSF would put more effort into solving and discussing todays problem, instead of solving RMS's printer driver problems from the 80s, since really, that problem has been essentially solved. We have today completely Free Software OSs that everybody can use. The problems that remain are outside the realms of the classic four software freedoms.
The software running on the remote server could even be proprietary software! For the sake of the person running the server, they should not use proprietary software, but if it is running on their machine and not yours, then it is not your responsibility, and (as I understand the GNU position) not wrong for you to access that software.
Now, if the software is actually a combination of server-side software and client-side software, such as servers that deliver Javascript code to be run locally, then that Javascript software should be Free Software.
But moreover, the GNU concern about running software on remote servers (i.e., "in the cloud"), is not just about the software itself, but about what the server maintainers can and do do with user data. Who owns the data? Can you get a copy of it? Can you get a copy of _all_ of it? How about the implications of the data? For example, you could tell Facebook ten things about yourself, and they could extrapolate a hundred more. Is "your data" the ten things only, and not the additional hundred extrapolations? And, if you ask them to delete "your data", will they? If they do, what exactly do they delete?
So it's really more of a privacy issue, I think, than a pure "free software" issue, but important nevertheless.