The answer is simple, matchmaking services have large databases of profiles, there is no single place where you can find so many people and then sift through them one by one, and so it is one of the best places to find your potential partner!
Various online matchmaking and dating services have made their mark today. Different services could be popular in different circles, communities, religions etc. Many umbrella services offer specialised matchmaking for people with specific or narrow search criteria.
Sites like findyourfacematch.com or eharmony.com have proved to be quite popular among people thanks to their high success rate. There are people out there who may say that online dating services never work, and then there might be others that say that they do work!
The point is that the world of dating, love and relationships is so subjective and personal, that it is impossible to decide whether these services work or not, the only thing you can decide is whether they work for you! And for that, you need to try using one; it could very well end your search for your perfect partner, or at least perfect date!
Dating sites exist because there is a need for them in society. Not only do they exist, but they have also proved to be quite popular, which is because they work for many people, but whether a dating or matchmaking site works for you or not is a question only you can answer!