Basically, imgflip is a website that provides funny memes to makes people laugh.
Memes are sorted in the hot tab by upvote and dates.
So, begging for upvote it like breaking Amazon's algorithm by putting all the keywords possible. It puts bad memes at the first place, that sometimes even breaks the rules of Imgflip (aka be respectful).
So that 1st makes people angry because their memes, that they put a lot of effort on it, got way less upvote than a blank template with "Upvote this meme right now *trollface with gun*".
And 2nd it's bad for imgflip reputation/community because more people tend to copy those memes, so there's less funny memes on the first page that people see when connecting to imgflip.
I hope that explains it all and I hope that wasn't too confusing or subjective