What's the deal with dating sites?

I have mixed opinions about dating sites and have had mixed success-some fun and some annoyance. They can be a nice way for people to get together and find a broad array of persons who may have something in common with them. Back in the day there was the Personals which was a real condensed form of the current venue. Rather than a paragraph, there was 1–2 lines-
*SWF wants a man in uniform who’s good with his night stick.
*SBM looks for Ebony Princess to take home to mama
Now there are sites like Eharmony and Match which administer batteries of tests, exclusivity clauses, and endless question and answers. The idea of which is supposed to push you towards the fine end of a funnel-to help you truly find that person who is perfect for you. I question the idea that you can ring up the perfect spouse like a dish at an all you can eat buffet. In fact all of my significant connections/relationships were with people who I never imagined I would be compatible with. What are your thoughts, experiences and take on this brave New World? I think that there’s no substitution for good old fashioned face time to really know someone.
Maybe it’s like dining. Some of us are adventurous and some of us want to know that our Filet O’Fish is always consistent with the special sauce.