"Gnome is a foundation with at least a few developers paid to work on it full time"
This is incorrect, the GNOME foundation does not pay any developers. They paid one developer once for a few years but they don't anymore. There is staff working for the foundation but they handle the administration, not development. Pretty much all development is handled by volunteers.
"They bring in almost one million in 'revenue' per year"
This is also incorrect. There was one year they brought in that much, and it was because of Handshake, and the year after that was another big one time donation. A lot of open source nonprofits also saw a bump in funding for that year because of that and the Pineapple Fund, that amount is not normal, take a look at their financial report for all the other years. Happy to provide more details here. That money was the only reason they were able to fund a developer, it was enough to fund literally one developer for a couple years, and now it's gone, so yeah. In fact I think the feeling at the foundation has been that they don't really want to rely on those big one time donations, because, well they're unreliable.
"My basic tenant is that when you make choices that make it difficult for developers to work with you, when you fail to cooperate and compromise, then you're going to suffer reputation damage. Reputational damage has all kinds of effects, one of which is that in situations like these people are going to look at what you say with a bit more skepticism. Another is that you're going to get people recommending against using your project."
Again I have no idea what you're talking about here. Please explain what choices and please explain who failed to cooperate. You are generalizing and it's not fair. If you want more info on what I mean, take a look at some of the GSOC projects that were done this year: https://summerofcode.withgoogle.com/archive/2021/organizatio...
These students are part of GNOME, they are newcomers looking to contribute in meaningful ways and help improve things, you may not care about those projects in particular but the new contributors may stay around and eventually fix issues that matter to you some day. When you make these sweeping statements you are lumping them in with everything else and it's very rude to these students to say this when they haven't done anything wrong or even participated at all in the disagreements that you were bothered by. Are you honestly saying you think they deserve reputational damage? And that's not even getting into all the other hundreds of contributors who also had nothing to do with any of your complaints.
"Gnome developers probably won't be open to collaborating on anything unless it directly benefits the Gnome project in a pretty major way."
I don't understand why you are saying this. That is every developer. Do you think KDE developers are going to work on something that only benefits XFCE? Or do you think System76 will stop working on their own desktop to do work on LXQt? I don't think they will, they will work on what matters to them which is their own projects. How else would you suggest they do it? I mean, I think it would be great if everyone was able to take a day out of the week to fix bugs in some other project but that's unfortunately not realistic.
"That's a very strong claim considering what I said was 'When does it become reasonable to assume bad faith?'."
I stand by what I said. Please don't assume bad faith. I used to do that often and I stopped because I realized it was just toxic negativity. It was making me miserable and I wasn't able to trust people or look at things objectively. It also was spreading to people around me and making everyone else become more miserable and cruel, that's what I mean by dangerous. It can really hurt people and destroy relationships.
"For example, I do believe that the switch to libadwaita is going to make things more difficult for people building apps on GTK4, because I think that they're going to move more and more important functionality into it and leave GTK4 to more or less waste away. I suspect that we're going to see a lot of stuff that could have easily been part of GTK4 become part of libadwaita instead, and that's going to make things measurable more difficult for everyone making GTK based desktop environments."
I am currently working on an app that uses libadwaita and I completely disagree with this. Most of what was in libadwaita was already stuff that was in libhandy in some form (and maybe libdazzle for a few things, I can't remember). Piling more widgets into GTK itself will just make things worse, it is actually a really bad place to put things if you want to iterate on widgets and designs, because everything that gets put there is going to be somewhat contentious. I have said this elsewhere, but if you sourced your information from social media then a lot of what you read about libadwaita is probably misinformation.