The main purpose of a dating websites is to remove impediments to love. Those impediments are biological and social.
We humans are armed with a set of biological behaviors that keep our body parts intact. Those behaviors maintain a distance between individuals that would eventually block love. For instance, we feel immediate disgust when forced to drink an other person’s saliva, but when kissing that seems not to be a problem at all. Besides, such biological impediments we share with several higher animals, all animals that posses complex behavioral patterns, vertebrates in particular. Biological impediments however, don’t play a major role on dating websites.
The domain of dating websites are social impediments. Such impediments come in different varieties.
Important is the division of labor. Many people because of their workplace fail to meet someone appropriate to fall in love with.
Other social impediments are more complex. They involve social pressure to keep the reputation intact or intimidation along a social hierarchy.