I think you may be misunderstanding the “free” part of FOSS. FOSS - also known as free software - is free as in freedom, not beer (this confusion is also why I refer to it as libre software). It has nothing to do with money - it is all about having control over the software that you use.
Some here have already pointed out the massive proliferation of libre software that forms practically the entire foundation of the Internet, but I would also like to mention that there are some projects that might even say that being libre software has made it more sustainable; for example, here’s a talk about how the GPLv3 (a copyleft libre software license) keeps the Samba project alive.
There are certain monetization approaches that are infeasible with libre software, yes, but I would argue that this is only ever the case with practices that are anti-consumer. Games as a service is a good example of this; I think it’s absurd you can buy a game that you should rightfully own indefinitely, only for it to become literally borked because it was specifically designed to always be connected to the game company’s servers which could be taken down at any moment. With libre software? You have access to the source code, so it’s not impossible anymore to get your own server running if someone else hasn’t already made the necessary modifications to make it happen.
The philosophy of (and reasons to care about) libre software isn’t quite the topic of this post so I won’t elaborate too much on it (unless you want, of course), but feel free to take a look at this page which discusses just that if you’re interested.
OP did say “wherever possible”, not “without any compromises”; I agree that it would be very challenging to try and live on purely GPL software, but it just seems like they’re looking for potential alternatives. I think it’s admirable given their stance on libre software.
This seems like such a blanket statement designed to put down copyleft advocates “because communism”. Do you think the right to repair movement - which advocates for control over one’s hardware (in contrast to software) - is also Marxist? I consider these two movements as practically adjacent to one another.
I ask the following more out of curiousity than argumentatively, because I still don’t quite understand this position: do you still encourage people to use libre software in this case? If libre software is better than proprietary software, why shouldn’t we strive for a world where all software is libre? Is there any reason for software to not respect its users’ freedoms? I’m not saying that we should all be hardcore GPL-only-or-die enthusiasts, either; rather that it seems reasonable to aim for a life free of proprietary software, one step at a time. In my opinion, copyleft can accomplish that better than permissive licenses would.