Even just 5 years ago this would have been unthinkable.
Women are supposed to be hotter and put effort into their appearance. As for the UK, oh my God yes, I know where you're coming from.
Thus you can only address men of a certain age, hobbies you like and, in addition, you can also see photos of all men in a catalogue.
So the chances you come across a man of your life are increased to a large extent.
Some of them are also too shy or too busy to go on dates and thus getting to know men online is the easiest as well as the most effective way for them.
Another advantage of online dating is the fact that you can look for a potential partner regarding you criteria.