At least for me, whenever I have to set up CI or touch CI, it's incredibly painful. I usually end up having to push a bunch of commits to debug stuff, and there's a lot of configuration hell. I don't know if Earthly solves this, perhaps it does. But if I were considering moving onto a new CI, I'd immediately think about having to redo this painful process. And that's at the team level. At the org level, switching CI would be even worse.

That does make me wonder, how much of CI adoption is actually moving from one provider to another versus new projects adopting CI for the first time? I'd guess that barring a really extreme reason, most projects pick a CI provider and stick with it.