I did a study of eHarmony years ago and came to the conclusion that only 10% of all "matches" were people who had the capability of returning a message.
I can quite believe that dating sites manipulate the numbers to look better themselves, and weirdly it's something that with my old school hat on is "not worth regulating" - but as we move to a world where most (?) people will find a partner online this way, being able to trust those numbers would be paramount.
(oddly perhaps such regulation would kill off the market. One of my wife's now divorced friends showed me her Tinder matches - and boy the pickings are poor for middle aged women. Now if you showed a parade of out of shape morons and then said actually only 2 of them are available, people might just stop the whole market and take up needlepoint)