Sure, on average, most women you meet through cold approach won't want much from you. They're in their own worlds, trying to do whatever they're trying to do, and you don't have that instant appeal for them when you approach. That gets better as you get better at targeting / sniping, of course. Then you start to approach more and more the women you can sense will want to meet you.
In social circle (or work), as women are exposed more to you, assuming you are a guy with enough attractive qualities, they will tend to like you more and more. The possibilities with you begin to open up. However, if they've known you for a while and you haven't flirted much with them or made moves on them or invitations, you become a fixture in their lives. They get used to you in that role of "guy I know socially, that maybe something could happen with, but actually nothing ever will." When you try to break out of that role, it's incongruous... why are you suddenly acting different? So their resistance goes back up. "Whoa, that's not Ben... Ben's never been serious about asking me out before. What's going ON with him?" I talked about that effect in this article.
There are ways to do the social circle thing well... basically by being the cad who is always making passes at women and flirting with them, so they never settle into seeing you as the "cute but harmless guy." It's a bit of a tightrope though, because you also have to not be annoying, and stay away from the women who will (in today's environment) use your overtures to throw you under the bus and advance their careers. Normally I'd recommend not dating at work, unless you've already handed in your two weeks and there's nothing to lose by taking your shots.
But yeah, as women spend time around you, possibilities that might've been closed before will open up. However, at that point you have to deal with the expectations you've set by NOT pursuing them aggressively early on... so there's another type of obstacle, another resistance. One way to think about it is social circle men are "cheap thrills" for women, because they feel lowered resistance around them, so can flirt with/fantasize about these men more, while at the same time knowing the guy can't actually do anything without being incongruous and causing their resistance to shoot back up. Usually it ends up being a sort of harmless flirtation (though there are plenty of exceptions... I think something like 60% of people end up dating/sleeping with someone from work. So it certainly doesn't always stay harmless).