Oh yeah, speaking of which.
Let's say the HDDT hards aren't as hard as their insane counterparts (with mods on the easier insanes or whatnot).
While I agree that, 1 HDDT hard shouldn't be worth more pp than an insane, if the insane is indeed harder. But one thing that these "pp farmers" have, is consistency. Some of them can go around and SS these difficulties in 1~2 tries, and instantly move to the next map and do the same. So if anything, this consistency should be rewarded in some way (allthough that's probably not what the pp system is doing currently, lol). SSing these difficulties in 1-2 tries is actually pretty hard from my experience, and it's much easier for me to, say hd+hr the insane than hd+dt and SS the Hard. People sometimes forget how easy to get 1x100 on maps.
Oh, and yes, consistency is a skil that probably quite a few lack. Just try doing the "pp farming" at the same rate as some of these "farmers" do, it's pretty hard. Then again, if you're superpro or something, you'll probably still say it's easy, but yeah.
I feel like I'm repeating myself like 2938 times in this post, so I'll just stop.