I am also "in the closet" on this. Sex is generally pleasurable; postulating a magic age or stage of development before which sex must be traumatic seems implausible on its face, without some other evidence. Coercion and intimidation are well-known to be damaging, but I don't understand how merely convincing a 10-year-old to let you stick something up her vagina (and then doing it) is going to do any more harm than, say, spanking her. Furthermore, looking at the historical record, the ancient Greek custom of pederasty (sexual/romantic relationships between adolescent boys and adult men) doesn't seem to have resulted in widespread trauma.
There are very few places in which it would be safe to propose this hypothesis, though.
Sex is generally pleasurable
Not "generally" over the domain in question. The pleasurability of sex is supported by brain-specific hardware that has no particular evolutionary reason to be active before adolescence.
What do you believe that most people on this site don't?
I'm especially looking for things that you wouldn't even mention if someone wasn't explicitly asking for them. Stuff you're not even comfortable writing under your own name. Making a one-shot account here is very easy, go ahead and do that if you don't want to tarnish your image.
I think a big problem with a "community" dedicated to being less wrong is that it will make people more concerned about APPEARING less wrong. The biggest part of my intellectual journey so far has been the acquisition of new and startling knowledge, and that knowledge doesn't seem likely to turn up here in the conditions that currently exist.
So please, tell me the crazy things you're otherwise afraid to say. I want to know them, because they might be true.