It's very sad to see this sort of thing (potentially) happen with TTRPGs. In video games, it at least makes sense that the rate at which the development company can produce content (or, more often, does produce content) is outpaced by the progression rate of voracious players, leading to a continuous cycle of players becoming enamored with the game, grinding out everything, and then leaving. Really sad when the same happens in TTRPGs because the possibilities are endless.
Which would be one of the (many) reasons why games need to be designed with serious care and attention.
If you don't support your brand-new players enough, they'll just leave before they can get invested, and the game cannot grow (whicn necessarily means it will die.) If you don't support your long-term players enough, they'll leave for greener pastures, albeit at a slower rate (because breaking away from a game you're invested in is hard).
But many games now are realizing that there is a critical middle part between "brand-new" and "long-term." It is genuinely good to make a game widely accessible, but too many companies have mistakenly done the trivial, damaging form of accessibility,
vacancy. If there is nothing to learn, then of course it is easy to learn, but it's also easy to
leave. I have seen multiple video games (not just MMOs) collapse and die as multiplayer experiences because the creators removed all possible challenge or rigor that might hinder someone's entry, and in the process, remove all possible things that might convince someone to stick around because there is no feeling of growth and mastery.
I fear 5e has coupled that with terrible support for the critical DM role specifically, and lackadaisical support for the intended play experience unless you have an already-good DM at the helm. That it has thus set itself up for a wave of new players who get in, get a couple of campaigns in, see some problem or other, and then based on that decide "nah, not really for me."