Very cool! One thing you’ll want to do is be sure Akismet is enabled, as we recently (within the last 2-3 months) added a feature where the Akismet plugin will scan new user accounts for spammy stuff and flag them for you thanks to @Roman_Rizzi 
Yes, completely human spam account signups – accounts that never post once, just set up an account with profile info and walk away forever – is indeed still a problem. The below is even after Akismet checking:
But bear in mind user profiles aren’t indexed at all, and new user profiles have seriously suppressed info… and our Akismet change helps tremendously.
Having a cleanup tool is still needed though!