>>16979
It's morally wrong to take advantage of weak and\or stupid people, which includes people under a certain age.
For example, it's wrong to scam elderly or naive people.
Now, (sexually) taking advantage of underage people is especially wrong because it creates fucked up lifelong trauma for that person. It's basically ruining the person's life and snuffing their potential.
And that's just the technical reason why it's bad.
It's also bad because groomers tend to be unnerving and dangerous people, and because people who were diddled invariably grow up to be extremely fucking annoying, like "daddy issue" type egirls and porn "actresses".