Feels like this is tyranny of easily measured metrics. If your north star metric is something more focused (number of fun dates!) that incentivizes features and experiments that push that number up, but if the number is DAU, suddenly you've decoupled "success" from the actual intention of the website or app. Obviously, "number of fun dates" is a lot harder to measure, relying as it would on surveys with low response…
Users use dating apps with the intent of not needing dating apps. A dating app that works well destroys it's user base. Their desired user base is people looking for hookups. Is it any wonder the apps have degraded into stuff pretty much only useful for hookups?