True. What you mentioned was always false.[1] macOS is BSD. Everything is a file in BSD. Anything that is a file can be deleted. Next time, try not to assume that something can't be done just because you don't know how to do it. Just assume you don't know how to do something when you don't know how to do it, not that it can't be done.
Ok, first of all, even if you are right, you need to not reply to people like that. It was bad enough already when you tried to teach me about BSD and how files work, but then for whatever reason you decided to go back and add to it and make it even more condescending and personal. That's definitely unacceptable here, and I doubt it is celebrated elsewhere on the Internet, either.
Second, and perhaps more awkward, is you're actually still wrong. I didn't assume that what you claimed couldn't be done because I didn't know how to do it, but because of, for example, the fact that I was actually at Apple when this change was rolled out, or that I've gone through the processes in the article you linked enough times to know how they work.
Anyways, turning off SIP does let you just go rm everything you want. That used to be the case, until Catalina, but it isn't anymore. In macOS Catalina those files were on a separate mount that was read-only, but with SIP disabled you could remount it as read/write and then work with it as usual. In Big Sur the entire volume has been turned into a signed APFS snapshot that you cannot modify, period. Even if you pull off hacks to patch it the system will panic on the next boot (as several iOS jailbreaks have found out the hard way). What you can do on macOS is shut down the computer, boot into recovery, disable signature verification, and from there create an entirely new snapshot with the modifications you like. With just SIP disabled and root permissions you can't do this, and even if you go through the process I described it's irrelevant whether macOS is a BSD or apps are in bundles because you're literally constructing a new copy of a APFS volume with the contents you want.
[1] https://developer.apple.com/documentation/security/disabling...