Just like with every fandom, the creepy people are the most noticeable. Instead of saying "Let's do a genocide on the bronies" why not say "Let's do a genocide on every creepy pervert ever"? Then you cover all the bases.
I'd agree with you, if these groups weren't the most amusing.
Or if as a defense mechanism I consider perversion as a sort of "lolsofunneh" thing. Though I won't deny there are those that take it seriously.