> If rebuilding the world from source is an option, changing the ABI is an option.

It's an option ... but not a very good one.

It tends to create an unstable environment that requires a centralized organization just to keep it working, precluding a healthy diverse software ecosystem.

This is a major reason why it's very difficult to distribute binary packages when operating externally to the distribution packagers, and why commercial software distribution on Linux is a massive pain in the ass.