4 was better than 3 as you had vbseo and dbtechs optimization tools but when you ran a large forum it was so resource heavy. Xenforo reduced my load by so much, it was such a huge improvement.
Historically, I would have a special hidden field for users to insert a phrase or a word in the event of this situation. They would email , I would ask for the secret word on the account and it helps mitigate.