I think it's an interesting question as to whether or not the OGL has helped propel D&D (especially 5e) into the position of dominance that it is today.
From where I'm sitting, it's very hard to see it any other way.
Again, there is a reason that open licensing isn't the norm in most fields, outside of coding/computers (which is where we find most examples and case law).
Yes, but just because something isn't the norm, doesn't mean it's smart. Countless things have not been the norm, then turned out to be the right way to do things for maximum success. Sometimes standard approaches are maintained for decades or even centuries despite some other approach being better.
And I think there's just no possibility 3E would have gone as big as it did without the OGL and d20 STL. The sheer amount of space that allowed it to dominate in FLGSes (back when were genuinely the primary way people acquired RPGs, particularly beyond the core books), and how important it made 3E look to a whole generation of RPG players has got to matter.
Without that, you don't get Pathfinder. Without Pathfinder, you probably don't get Critical Role (if claims that they didn't like 4E all that much are correct). Without Critical Role, 5E just doesn't go as big as it did.
Indeed, I think we can go further - if it wasn't for the huge success of 3E which was in part built on the OGL and d20 STL, and ironically the success of Pathfinder, would we even have 5E? I'm not sure we would. 5E was the "apology edition" designed specifically to get people back from Pathfinder, by hitting the weaknesses of Pathfinder (like being overcomplicated and poorly balanced) whilst also trying to retain D&D characteristics. If we change history a bit, and there's no OGL, and they probably either don't have or quickly discontinue the d20 STL, I don't 3E ever achieves the market share it did. I don't think plans for 4E are particularly different, but probably there isn't even a GSL, and 4E would still be very divisive. And any competitor people flock to wouldn't have been a close D&D relative, but a different game (hard to say what). I don't think WotC would have made a 5E that was like our 5E in that situation. I think they'd probably have tried something quite different - quite possibly doubling down on 4E, just trying to get the tech angle right this time, which, by say 2015, might have worked.
That said, for most brands (thinking of D&D as a brand, not as a game), this isn't about just leveraging the brand for maximum profits. It's also about control. Control over who is licensing your product. Control over what they can do with that license. Control over the kind of content they can make.
Obviously true but if you're doing this irrationally, it's not very helpful. As far as I can see, most of the successful OGL companies, particularly those ones making stuff for 5E (who are the only ones 100% definitely no question impacted by the OGL 1.1 - others you can argue maybe it's opt-in), haven't caused WotC problems with control.