Adopting Anonfilly probably saved the site at a time when posting rates were abysmally low, like down to 100 posts sitewide per day or less on most days. Plus they were pretty much fucked over by the janny at /mlp/ and their whole community would likely have died off if we hadn't given them a home, so it's been mutually beneficial. Just because their threads are large and move faster than other threads on the board shouldn't be taken as proof that they don't contribute to the rest of the site because they clearly do. Having a few neverending threads on the board is a small price to pay for at least having a board in the first place, and it's a fair sight better than being like 8/pol/, where the front page is nothing but stickies and nobody is allowed to have any fun. Most threads stay in our catalog about a month on average and if you feel a thread is not getting enough attention you can always bump it to keep the discussion going.
Personally I wish people would stop trying to force /mlpol/ to be one thing or another and just let it become whatever it wants to be. Imageboards have always been an amorphous culture, continuously evolving and changing as individuals come and go. /mlpol/ itself is merely a single step in the evolution of the greater imageboard culture, which frankly we should all be happy still exists after all this time.
"Anonfilly did nothing wrong!"
-- Based Tyrone