XP never claimed to invent any of those practices. But they were unevenly distributed. I note that 1998 was ~25 years ago, so I'm not sure we disagree here. You just described CI as a new-ish practice you adopted from another team.

I'm happy you had your experience. But I will testify I've seen lots of places that would slap your hand if you touched code to "clean it up". When "testing" was two people running a week-long manual script, narrowing the scope of changes was a required practice!

As for developer testing: a core idea of XP is that we developers should take responsibility for the quality of the code we ship. Test-first was a practice to support that goal. Automated testing wasn't completely unknown, but many shops had zero automated tests. Or if they had automated tests, they were clicky-clicky tests run by a ui-automation tool, and were written by the testing team. Developer written tests were rare back then. I remember interning at MS in the 90s and how proud they were that their target tester:developer ratio was >1! The creation of JUnit was an important historical event for us.

As for the lack of communication and wasted work: I completely agree. Turning a story/use-case problem statement into a concrete design has to happen sometime. We used to do a whole-team tasking meeting for each story we opened, and group estimate of our tasks on the whiteboard. Combined with pairing, whole team rotation, and continuous integration, there was very little opportunity for someone to get lost.