It is not good for a scene to have one or two dominant players. That's not a healthy scene; that's one spiraling the drain, soon to expire.
"Are you talking about D&D again?" Not exactly.
Tabletop RPGs. mecha anime, and a few other notable entertainment business niches have this issue dogging them and it's never a sign of good health. It is in the interests of the dominant party or parties to ensure that there is a marketplace filled with competition that isn't nominal and token in its character (the case in tabletop RPGs for decades now, despite itself at times), because those will have to come up with means that give them a real and substantial competitive edge over the leader(s) in order to attract and retain an audience of customers- means that inevitably come to feed the leader, so long as the leader isn't somehow usurped.
Why is such dominance bad? It ossifies the category, making over-rigid thinking the norm and turning the category increasingly fragile over time to outside-category competition. Furthermore, you start to see more resorting to using state power to defeat any competitive threats instead of retooling to face those threats head-on, and once that starts other monopolistic practices soon follow.
Mecha anime is dominated by the Gundam and Macross franchises, especially Gundam, and the effects are particularly felt in Real Robot competitors who have to either incorporate tropes those two founded and codified or find some way around the expectations set by those tropes in order to attract, retain, and satisfy an audience.
D&D has so dominated TRPGs that it's all but choked-off possible competition, and that monopolistic influence extends into videogame RPGs of all sorts (and from there to spinoff genres like MOBAs).
Western media SF is defined by Star Trek and Star Wars, with a few others distant after that (B5, BSG, SG-1, DW, and a few others) so the rise and fall of those two can foster or kill entire categories of media businesses (RIP Toys R Us).
In short, I do not talk of things only possible; I'm talking about what's going on right now.
While one individual can only do so much, our efforts taken in aggregate collect into something substantial and potent. I said to others on Gigguk's video on mecha anime that fixing the problems with the business is on us--the fans of the genre, worldwide--and that is how #AGundamForUs began.
I've gone on about tabletop RPGs for years; some folks some years ago decided to do something about that and the Old School Renaissance got started. The Supreme Dark Lord decided to do something about the DC/Marvel poz problem, so that's how Arkhaven Comics got going and even more is on the way- and not just from him or his immediate allies.
I'm sure someone's figured out how to make their own anime without spending 15 years to make one feature film or submitting to the stupid work environment of many a Japanese studio (or Disney before that); I just haven't heard it yet.
Just look at Mark Kern. He's doing all this sort of thing and more for his Mecha-v-Keiju game, EM-8ER; if he can do that and still make time to do Gunpla with his boy, we can figure out how to make what we want to see.
The point is this: we are the ones that will solve the problem described above. No one is going to do it for us. It's time to get in the arena and fight for what we want, because no one will do it for us- they don't have the time, the desire, or the willingness to Git Gud.