For a top (literally top -- now #1, congrats) memer like you, getting bombarded with spam, irrelevant begs for attention, and hate/abuse must be exhausting.
The Imgflip community is great, it's why we're all here after all, but sadly sometimes you run into toxic users -- it's inevitable.
But especially top memers like you should be able to have the option to focus on just memeing their awesome content and cut out the crap. So, I always support enhanced options for dealing with trolls and spam, to empower the Imgflip user experience and keep the flow of good content coming.
So like you say, the option of not just blocking but banning certain memers from your own memes and streams should be considered. That feature can be abused, potentially (just like every other feature of Imgflip can be abused, tbh), but not in the right hands. Maybe this could be a feature you can unlock once you hit a certain point or streams modded milestone, indicating your experience and judgment.