This feature has been working very well @sam 
I think the previous implementation you created could still be quite useful as an additional anti-spam feature, it worked incredibly well for the short time it was available and enabled (default off).
Otherwise spammers can still create bulk accounts with one gmail address prior to a moderator or admin noticing. E.g. Creating the accounts but not posting anything immediately.
Admins/Mods will need to manually find and open each individual account to ban/delete them. Which can be quite tedious, especially when one spammer can create hundreds or thousands of accounts with one gmail prior to being banned. Also as searching for the emails is difficult e.g. j.ohan.2.1@gmail and jo.ha.n21@gmail.
If they aren’t manually hunted down, then the spammers keep a large pool of accounts to play whack-a-mole with, while only needing to expend one gmail account to obtain them.