In fairness, closed source software is a very very tiny minority of the software available on Linux, which is why ABI backwards-compatibility hasn't been much of a concern. In that respect, it's essentially the polar opposite of Windows and even MacOS.

However, it'd be very nice if it did become more of a focus (especially in the glibc/audio/glx areas), especially now that gaming has become very popular on Linux.

Trying to get old, closed-source games like Unreal Tournament to work on Linux can be a real chore.