Why do some young women think the interest of older men is "creepy?"?

In another question, a sixteen year-old girl said she found the attention of older men (above 50, I think) to be “creepy.” This is not the first time I’ve heard this, and it makes intuitive sense, but still, it makes me wonder if anyone could talk about what, exactly, it is that they find creepy about it.

Is it a natural rule that people should only be interested in people of their own age? Is it that younger women don’t take themselves all that seriously, so they don’t see why a (supposedly) mature person should? Is it that they think the older men only want sex? Is it that they think the men want to take advantage of them in some way just because the power levels are different?

If you have experienced this, I’d like to know what you think made you feel creeped out. Otherwise, if you have a theory about it (political or otherwise), I’d like to know what you think.