As a really quick point, dating sites are quite explicitly not built for men.
They acquire men at a far higher rate than women, and men ~tend~ to be the ones approaching women, and so pretty much every feature should (from an objective point of view) be designed to filter out men that women aren't interested in, so women receive fewer attempts at interaction from them.
Your dismissal of the importance of not wasting the time of men doesn't work if higher quality men have more of their time wasted.
That is, if the men who write detailed messages get worse results than the men who write a thousand identical one-liners (or who swipe right on everything, etc.), then the former type of men will leave the site and women will be left with the latter type.
The key flaw is the assumption that the pool of men is unchanged compared to an active strategy.
if higher quality men have more of their time wasted...
Or shift their attention outside the service, as both you and the GP have said, either to another service or IRL activity.
I and another couple I know of are married/engaged 5 years after meeting on OKC.
There's nothing more exhausting as a guy than to write messages and basically get very few if any replies.
One of my best friends is like myself, a person of colour, and his response rates are putrid despite putting good efforts in writing interesting opening messages that relate to the persons profile.
If you think this is big, by the way, make sure you take a look at their post from December 11th:https://theblog.okcupid.com/why-okcupid-is-changing-how-you-...