With respect to the apps, you have to realize the filtering problem comes to a steady state, where new "dateables" in equals "datables" out. This isn't necessarily a problem
Unless the "undateable" person gives up and accepts staying single forever, they may stay on the platform for a decade or more. Maybe with decreasing activity/time investment, but still an active user eligible for matching. That's longer than I'd expect a dating platform (or any random software startup in general) to thrive.
It would seem that the obviously good solution to this is to hide profiles if the user hasn't been active in a certain time period. Say, 30 days?
Of course, that's not good for the company metrics. They have to inflate their numbers somehow, and so including accounts that aren't being used anymore in their subscriber count makes them look good!