Reminds me of Apex quite a bit (although note quite the same timescale). Interesting observations of why keeping legacy logic working is essential.

In the Emacs world (and in many other domains, some of which we’ll explore below), when they make an API obsolete, they are basically saying: “You really shouldn’t use this approach, because even though it works, it suffers from various deficiencies which we enumerate here. But in the end it’s your call.”