Replace Rust with Bevy and language with framework, you might have a point. Bevy is still in alpha, it's lacking plenty of things, mainly UI and an easy way to have mods.
As for almost everything is at an alpha stage, yeah. Welcome to OSS + SemVer. Moving to 1.x makes a critical statement. It's ready for wider use, and now we take backwards compatibility seriously.
But hurray! Commercial interest won again, and now you have to change engines again, once the Unity Overlords decide to go full Shittification on your poorly paying ass.