I think focusing on the OGL is too small of a view. Yes, it was a contentious issue, but it was only one piece in a string of questionable decisions that fumbled the brand.
At roughly the same point in time, D&D brand had a best selling video game, a critically acclaimed TV show featuring the product, and a big anniversary date to celebrate. For once, there even managed to be a pretty good D&D movie as well.
Yet, despite all of that, virtually none of that was turned into goodwill with the customer base, better brand identity, or better community engagement. The proverbially stars were aligned, but virtually nothing happened. In some cases, worse than nothing happened; choices were made that snuffed out all of the positive momentum and fostered negative sentiment among the customer base.
For specifically the OGL, I don't know who "won: or "lost." In the end, WotC still did essentially what they wanted to do anyway, but the path the company took to get to the same location involved a lot of unnecessary turns that squandered what had previously been overwhelmingly positive brand visibility and momentum.
I think, if anything, the main change over the past few years has been people being more aware of and more willing to try other ttrpgs. Obviously, WotC's D&D is still the industry leader. But I still think how WotC went from all of the positive momentum they had to where they're currently at should be studied as an example of what to avoid doing as a brand.