There are many Shidduch sites out there. The very fact that they exist show that people are "falling out of the system" of using a Shadchan. One such site (which I know made a shidduch for my brother-in-law) is Saw You at Sinai.
I could wax eloquently about the importance of a good Shadchan, etc., but unfortunately for many people they don't have access to a good Shadchan, just someone who gives themselves that title.
Why there is a "shidduch crisis" has been talked about at length, if there is one, which groups have one, etc. The currently popular thinking in Litvish circles (there have been multiple articles in the English Mishpacha and Ami about it that I have seen, and I'm sure there are others) is that the age gap between the boys and girls is too large.
My own observation of the Litvish community is that they have a major expectations problem at many levels. When your expectations are unrealistic, it makes a Shidduch very hard. I'll tell you the story of a guy who was looking for the "perfect" woman to marry. He met very many, spent many years looking, and finally he found her. But they didn't get married - because she was looking for the "perfect" guy.
I don't know that it is hard to build such a site (there are several, some are general like Saw You At Sinai, others can be community specific) is not necessarily hard, but it is going to be for some sub-section of people who are not going the traditional route, so it is going to have audience challenges.