I agree with this. I was working on a project that was only available with Mercurial and I spent three days just trying to figure out how to not irreversibly corrupt my repo for a one-line change. I never figured it out and gave up since it wasn't super important.
I was happy when Atlassian finally sunset Mercurial, forcing those repositories to move to git. I'd rather all major source code hubs standardize on git since it's harder to contribute needing to learn different incompatible workflows.