@orangeandblack5, This may be a way of preventing them from creating new accounts - at least for a while - if they are using certain words or phrases in their usernames.
Change your settings in
must approve users (Staff must approve all new user accounts before they can access the site).
Based upon their past usernames, you could route out many before they get a chance to start. Eventually, they may be “creative” enough to find a workaround. A possible solution to them opening an account with a “valid” username, getting approved, and then changing their username before they go on their liking spree would be to prevent users from changing their usernames as well. How many people actually go about changing their usernames anyway? Those that do can ask staff to do it if they are not allowed to do it themselves. Hope this can help a little - at least temporarily.