Because lolicon implies a clear divide between fictional and reality content and shows that the left are permissible of ANY sexual perversion so long as it can be done in reality.

I'm willing to say, the vast majority of 'lolicons' are safe around kids as they know ones a fictional drawing or a bunch of pixels so they can draw them doing anything but in reality, no, that's a child (unless your that one chick with that medical condition) and they should never be subjected to anything sexual or adult.

By comparison, the left have ALWAYS had a weakness believing their delusions can work in reality (cough communism) and its why there's been such a push by them on the trans/Necromoph front. The ultimate delusion of believing you can 'change sex' and that children can consent to sexual and adult content. Couple that with the thrill of corrupting usually SOMEONE ELSE'S children and you end up with the current era of drag shows and modern education. Give it a year and they'll start saying it's fine to fuck corpses as they already are pushing beastiality in Spain for example.

TLDR; Trans/left hate lolicon because it illustrates they can't keep their perversions in fiction only.