Also the main issue I see with 'modern' Linux ecosystem actors, is that they usually do not put on the 'market' a new product that they developed (from scratch or after forking a traditional one); instead they first take control of a an existing piece of software or project, and then they change the way it works, or the direction it takes, or make it un-portable just because.
I wouldn't mind if they released new software, new concepts, new OSes and let the users (the competition? the free market?) choose. If they take the market share, good for them, but they didn't have to come and screw with the ecosystem I picked years (decades, actually) ago. Let the different ecosystems leave their lives. I chose this one 20 years ago especially because I wanted to avoid those things which, now, are put down my throat!
Would changes (switching) take a longer time to occur? Yes, probably, and I don't think it is a problem, considering today's tendencies in software development which exhibit more problems because of going too fast.
For example, I never read any user saying "I moved to a Redhat distribution because it has systemd, that's so much better" before a couple of distro maintainers (soon to be hired by Redhat) decided it had to be imposed on a distro and then another. Nobody really cared about the supposed advantages brought to the table by systemd, nobody demanded it. And yet...
Same thing for major changes of/in GUI toolkits. If they want breaking changes (as toolkit devs), if they want a complete redesign (as toolkit users), just fork the existing project and name it something else at least a little bit distinctive. Let the project as it is a chance to survive (no matter how small that chance is).
But no, they want a monoculture, they want to spread it as much as they can, and force everyone to follow their way, their idea of the day.
In fact it is a bit like globalisation, where a single culture, a single economic system, a single social system is supposed to eat the world and leave it with a single boring monoculture, the same everywhere.