Exactly. D&D only becomes profitable because of network effects. Grow the network and reap the benefits in the long term. It's exactly the insight that had Dancey create the OGL and the SRD in the first place - better to have 3pp supporting D&D and growing the game Wizards would profit from than to have everyone fracturing the market into tinier networks that weren't supporting D&D.D&D is only the gateway if enough people play it. To keep it as the gateway, funneling money back to you, you need to ensure the maximum amount of people play your game or use your rules. You accomplish this by getting the game so big that everyone plays it and keeps playing it.
And it was controversial at the time among game creators precisely because what the end result could be was one system to rule them all, one system to bind them. Everything becoming D&D. And if you are not a fan of the D&D model of gaming, or you don't trust that one company owning D&D would be a good steward for the entire ttrpg industry, that sounds awful. The market actually looked like it might go that route for about 3 years until Wizards made their first product blunder - releasing a 3.5 edition of the game that was just different enough to invalidate a whole bunch of 3.0 products on the shelves just 3 years after the initial release! That was the first point where companies that were doing third party stuff took a step back and started saying "do we really want to hitch our wagons to Wizards' business plans too tightly?" The first real point of broken trust, if only a minor one compared to the ones that would come.