yes, the "which one is correct" problem is real. I don't really know the answer to it, but I've always had a bit of a knee jerk reaction against a single dominant implementation.

One counterargument is that every single version of Core is really a separate implementation and we could just as easily have a problem where a new version disagrees with a previous version and we won't know which one is correct.

Personally, i think I'm willing to risk the messy situation in order to have options.

As to cannibalizing engineering resources: there are quite a number of very good developers who don't work with Core (for various reasons), and in the case of a dominant implementation, it's not surprising that there are interpersonal conflicts (we are all human). The problem is it's hard to do any effective work without someone or some group being in charge.

I've also appreciate Jon Atack's commentary lately. He strikes me as someone who is a solid engineer, but who has found it difficult to work with the main Core repo. I don't mean to imply that Core engineers have done anything wrong, but rather that it's difficult to expect all people who want to work on Bitcoin to get along with the leadership of a single project.