I remember a while back this artist made a post about how he was depressed that his artstyle hadn't improved. But I tell ya, he's perfect just the way he is.
Things like vore and scat and stuff like that are physically disturbing. NTR, (Or Netorare), is emotionally disturbing. Nobody is gonna kill themselves because some weird **** like vore or vomit happens. But someone get's NTR'd or an emotionally unstable person gets into an NTR comic? Not good time.
NTR (Or Netorare) is literally a fetish derived around the main characters primary love interest being stolen from them by someone else through sexual means. Often without them initially knowing until the very end. The parallel to this is Netori, where the main character is the one doing the stealing. It is intended to invoke feelings of jealousy or envy and is, out of any fetish, one of the most emotionally detrimental.
Oh, i see :o So people hate it because it can give an unstable person wrong ideas? Shiet... Didn't think about that; i mean, its a bunch of drawings goddamnit
Not to mention like... The general concept behind it can be explained with it's translation. Netorare literally means, "Stolen through sex", (the other version being netori, stealing through sex.) But when a girl gets stolen from a guy, the guy who lost her is deemed as weak. Even moreso if he derives some sort of arousal from her being with the new guy. (See; Cuckold)
After further review, pretty sure "he" is either a "she" or "ghey" because they have a strong affinity for yaoi undertones.
Though, to be fair, it's everything they draw is still amazingly cute.