> Some did, sure.

Not some. I mean, even the few source code repository services that supported mercurial started dropping it.

See Bitbucket's announcement:

https://www.atlassian.com/blog/bitbucket/sunsetting-mercuria...

> According to a Stack Overflow Developer Survey, almost 90% of developers use Git, while Mercurial is the least popular version control system with only about 3% developer adoption. In fact, Mercurial usage on Bitbucket is steadily declining, and the percentage of new Bitbucket users choosing Mercurial has fallen to less than 1%.