Let us try to examine the opposite direction and dream how the world may look like without 100% free dating site, what problems humanity may have without such services.
By supporting these free dating sites with your own membership, you ensure that it will remain "cost free" by convincing advertisers that there is a market of people to reach with site ads.
What if your perfect couple lives in another city or even country?
You may never meet each other and live separately with different people, trying to assure yourself that you are happy.
While there may have been a time in which the cost of a paid site screened out the riff-raff, that time has passed.
In 2017 everyone wants to save money and when there are totally free dating sites that offer quality people with good jobs and education, there is no reason not to choose them and go to paid ones.