And yet none of those "outsiders" have figured out a way to economically renumerate developers for their work. Flathub had a initiative a few years ago to add payments to help developers fund their projects, but I haven't seen anything come out of it.
I'm not sure what you're talking about. I can download Blender from almost any package manager, and the devs of Blender are paid.
Most linux distros require that software they distribute is open source, and link to the home pages of applications, so effectively donations are the only way to pay for those. There are paid distros (which are almost always about support, there was a paid GNUStep distro though many years ago).
On the other hand, Steam et al are app stores where developers can get paid.