You haven't been using the LSP API then. There have also been multiple breaking changes over the last five years, including breaking compatibility with established default vim keybindings.

A documented breaking change does not mean the application is unstable.

The Neovim developers have been extremely clear that part of the process of getting to 1.0 is finalising the API, and that there will be breaking changes en-route.

I have never experienced this many breaking changes in stable software. There's a reason nvim still hasn't hit 1.0

To be clear, it's fine to have breaking changes. Especially if you're working towards something substantial.

But nvim and its plugin ecosystem seem to be altogether too keen to change absolutely everything and adopt all bleeding edge developments. Even when a mature system would serve the purpose just as well.

Changing default mappings is not a "breaking" change.

It is. And iirc, neovim themselves mark them as such.

We may mention them in `:help news-breaking` for visibility, but that's only because I don't care about pedantry. API breakage != UI changes (e.g. mappings).

API breakage != UI breakage, yes, ofc. Because API != UI.

But the UI is also an interface, and the user is part of the total system. That system interface is broken if you change default mappings.

It doesn't matter if the interfacing component is software or a user.