Board Thread:General Discussion/@comment-38788660-20190328124724/@comment-1038387-20190328191359

Admins can block for whatever reason they see fit, including no reason. If an admin suspects a user is an alt of another, they can block them for abusing multiple accounts. They don't need to verify with CheckUser. If the usernames, edits and/or time frames of contributions are similar enough, that can also be an indication. Doesn't have to be, but if an admin thinks it's sufficient, you hang.

And yes, B is infamous.