We do have questions like those enabled. They end up figuring out the answers and just create tons of accounts. That is what happened yesterday. One of the changes I made was to the validation questions. I do like your summer / winter question, I will add that one to the rotation.
Separately, I enabled an additional third party service CleanTalk to the validation workflow. It will continue to process checks for at least X messages after a member sign up and enables automatic blocking of languages and regions.
Unfortunately, over the 15 years of this forum spam bots have been a constant game of whack-a-mole.
Sorry about this issue.
Dan