Everything related to this issue is anecdotal evidence. The typical argument, "What if the elder person seduces you and uses you?!", is just as "logical" as, "What if that immigrant we import turns out to be terrorist?! Better close the door!" There are cases when it happens, and there are cases when it does not happen, but in controlling cultures (which are all civilized cultures nowadays, AFAIK) people decide to pick ethereal security over real freedom, and not only for themselves, but for everyone else.
Personally, I don't care if a 8 y/o girl has a relationship, even sexual, with a 60 y/o dude. If the dude uses her, then it always can be brought to the court. If not, then it is nobody's business. The whole "age of sexual consent" thing is nonsense, IMO.
But I know that saying this nowadays means that everybody, regardless of the political leanings, hates me, because one isn't allowed to have unconventional opinions.