Yes, you're absolutely correct. The GPL, and resulting GPL'd software, does not exist for the benefit of commercial software vendors. While some business models are viable under it, that's a side-effect rather than an objective of it.
i.e. it's condemned to be a hobby for almost everyone involved, besides some key players who can live off of donations or those who sell services based on mostly other people's software.
Selling services 'based on mostly other people's software' is not some crime or bad thing. Servicing cars or houses made by other people is an honorable profession. So are software services. If the thing needs servicing, then I salute those who stand ready to do the dirty work.
And I didn't say it is. Only that it's usually the only way of building a business around GPL software. This is fine for serving some people, but it has a huge blind spot for those who mainly want to write Software and try to live off of it. IMO this is the main reason why Desktop linux never took off - you just don't have enough userland software that's ready for production use in a professional environment - see desktop publishing, audio, video etc. This sort of software is not going to be written as a hobby, it needs full time professional developers and investors who can see the ROI starting at around 1M$.
And to many it's fine if it is. The GPL wasn't created to benefit the software industry, it was a reaction to it. That's also part of the reason that some commercial interests (most famously Apple) have been moving in the direction of MIT/BSD-style licenses. It's OK to align your efforts with licenses that match your requirements. The GPL is most aligned with the interests of users, not commercial developers. MIT/BSD is the reverse.
