I personally hate the stupid anon self-insert trash more than I hate Flash. They are pretty different though, to be fair to the self-inserters. I hate Flash because I don't want to be cucked, but I hate anon self-insert fantasies because they are so horribly detached from reality that they just piss me off. The idea that the faggots on this board have enough self-confidence to envision themselves as chads in another world really makes me angry. It indicates a profound lack of self-awareness.
That being said though, I do self-insert, but I self-insert as Trixie much of the time, she's the most relatable character next to Glimmer. That scene you posted in the OP was very satisfying: based Trixie stops chad and stacy and saves the day, and proves that, whether mind-controlled or not, she's still the exact same loser on the inside and out. Trixie is my fucking hero.