Well, my usual example is the NAT/FW code. How many times has that been swapped out over the years? Three? Each incompatible with the previous.

How many attempts at a /dev filesystem have there been? How often did that break existing things? Glibc incompatibilites have abounded. Gcc problems. The list goes on and on.

And I intentionally use "they", specifically because it's not a single entity. And that lack of a single entity is the cause of many of these problems. It's not as if it doesn't create some good things, too. There's a lot to be said for a lack of monopoly (though RedHat had something of a de facto monopoly for many years), but it also results in incompatibilities, reduplication of effort, etc.

And, yes, I recognize that "Linux" only really applies to the kernel. You know what I mean; don't be disingenuous. If there was a better term for what I was talking about, I'd have used it.