Not to work this point to death, but doesn't the example you provide support my side of the argument rather than yours? You write: "We look at profiles and think oh wow he/she likes this or that, they think this or that, we should be a good match --- but then you can't even get a hello from them". Exactly. It doesn't matter what they say they're looking for or what they write on their profile -- if you respond and they don't feel any affinity or chemical tug, you often won't even get a hello. People don't always know what's best for them,but at any given point they do tend to know what they want even if they can't articulate it. So two guys say hi to the same woman and she knows pretty directly "THAT's the one who interests me". And the other guy should just swallow his disappointment and move on.
I should say that I DID once talk a woman into a nearly two-year relationship. More accurately, I talked her into a one-year relationship, and after a pause, back into it for another six months or so. Then I made the pitch for marriage, she freaked out (her previous marriage, many years before, had been traumatic) and dropped me by email. I called her and said "Sorry, after nearly two years an email dump is just not acceptable, I'll take you out for a bite and you can dump me in person if you really want to". She agreed, we met, I made my (tactfully revised) pitch again, she said she'd think about it, and sent another 'no' email three days later. I'm not bitter about it -- she's a good person, just, um, a bird with a broken wing -- but I present this little tale as Exhibit A in support of the case that you just can't keep someone interested in you, whatever you do, and that most effort in this direction is simply misdirected. From one point of view, I could be said to have thrown away two years -- under the mistaken belief that if I only said or did the right thing, all would work out. Now I see that I was in the passenger seat to a much greater extent than I'd realized.