I've often wondered if the main hindrance is distance.
I've met several people from this site in person over the years as friends, and the biggest hurdles were always saving the money to go and coordinating the times when everyone could get off work.
I've know many, many people here who found someone special, but it often didn't get to meeting in person or, even if they did meet, couldn't be sustained because of distance and money, especially if it was international.
I'm going to piggyback off of this because I think Seoul is absolutely right about the distance thing. She and I have talked before about long distance relationships and I keep saying the bottom line of an LDR is .... at least one person will have to pretty much uproot their entire day to day life to make that relationship work out. So that's a much bigger issue to progress that relationship than if the two of you live in the same town. And for most of us, even moving an hour away would mean that we change where we go to church, what stores we shop at, what clubs or activities we regularly attend, etc.
That makes the relationship much more costly than if it's with someone who already lives in the same town and goes to your church and you already have some common life and community elements.
But the internet also spoils us with too much choice which leads to us not making any decision at all. If you know your options are hurry up and marry the best guy in town / a good enough guy, or get stuck in a marriage with someone you don't want to be with, or be alone, you're probably much more willing to overlook imperfections in the good enough guy and be glad you didn't get stuck with someone worse than if you think that you have access to millions of guys and a better one is just around the corner.
And then the last subtle thing I see is that we've kinda lost the art of the date. You can be dating someone without going out on many dates, but as men and women are around each other more socially the line between are we doing something just as friends or as a romantic outing has been blurred a bit (especially if you're trying to keep some physical boundaries).
So practical advice if you really want to be with someone, find the person you like most in your immediate surroundings and give them a fair chance. And find new ways to say what you want and express your intentions rather than relying on words that no longer have such clear meanings. Or there's always the option of being happily single and doing other stuff instead of navigating the minefield that is modern coupledom.