"My entire point is that I can't see any kind of quality girls going on those websites."
You are very wrong my friend.
Frankly free is neither here nor there. For the amount of time you will spend the fee is totally irrelevant. Fab is free, though loony tunes because of it with more timewasters per square foot than anywhere else.
As for why women use them in preference to free sites, generally they don't want any drama or love sick puppies following them around. They also don't want their family or kids finding their profile.
NSA is it's own art. Displaying your junk is one way, but showing discretion and maturity pays off far more handsomely.
As a newbie you'll be hit up by lots of HBs trying to get you to buy into other sites ( verification links etc). Just report them, probably some fat bloke in a call centre somewhere on commission, and they soon stop.
Haven't had a problem with bots, I know they exist from the code but of the 200 or so lasses within a couple of miles I've had human replies from most that have been online.