While I’m impressed at your ability to stick your fingers in your ears & ignore everything else to the contrary, you might be surprised to know that the player numbers for a seasonal game are … seasonal (in English that means they vary over time with natural peaks & troughs).
The MG is unlikely to be the reason why many of them have left (temporarily or otherwise), the lack of new end game content is a far more likely reason. Hell, even the hit-flash is likely to be a bigger reason, as is the lack of non-gender locked characters.
You also need to understand the difference between a UI & the underlying system.