What's truly funny is that this isn't the first time this happened. 4th edition had WotC bamboozle third party creators by fiddling with the OGL, and third party creators responded by making a rival to D&D. They called it Pathfinder.
Then you look a little further afield and you see a massive indie TTRPG community that I have to assume had an influx of new designers who only found out about it due to the OGL incident.