Compatibility is absolutely essential; that's why there's only room for about two and a bit mobile OSs.

Competition can only work for things that are componentised and un-bundled. Since both profitability and security work against this, we end up with competing monoliths where you have to take the entire bundle of features and anti-features.

Competition doesn't necessarily imply that it bypasses sunk cost fallacy, or even that the competition won't do the same nonsense in a belief that feature X must be wanted.

See recent versions of Gnome and KDE Plasma