Goes the other way around too: Linux will only have a good desktop environment when it's users will be willing to leave it.

> Linux will only have a good desktop environment when it's users will be willing to leave it.

Putting aside the debate as to the quality of desktop environments, I honestly hope you're being intentionally nonsensical as a joke. What you describe can only make sense under the grossly misinformed belief that "Linux" is a monolithic entity incentivised to stop its users from "leaving it", and that this mythical "Linux" would have the agency to decide it needed "a good desktop environment" in order to avoid that from happening.

I recently started using COSMIC and I would definitely call it good, even if it has a few rough edges due to just recently coming out of beta.

I mean, from my perspective Linux has multiple good desktop environments. I've used both Cinnamon and KDE for years and have found both perfectly pleasant to use.