Regardless of how flawed early D&D was, his greatest contribution to modern gaming has little to do with that. What is important is how he worked to get it to be the most recognizable TTRPG. Live him or hate him (and there are many valid reasons for both) he made that happen, did he have help, of course, but it is hard to say he wasn't the driving factor that made D&D the most recognizable game in TTRPG'S to this day. Heck it is hard to find a RPG video game that isn't influenced by D&D.
It just gets tiresome to deal with people bringing up his many short comings so often when his name is mentioned in a discussion when he has influenced so many games in so many mediums.
Plenty of people throughout history have made wonderful contributions while being severely flawed, can we not separate the good from the bad? Reddit is full of stories with far worse people doing far worse things in the TTRPG space than Gygax did, and they have contributed far less to the gaming community.