From my quick read through of their methods it seems like they didn't account very well for the types of games, platforms and demographics. The decade in question saw a massive explosion of gaming as a hobby into the mainstream and, importantly, a strong growth of women in the gaming population.
So as a whole you have games becoming more mainstream to younger ("woke") audiences and more accessible while the inclusive-biased demographics also blew up. It's not at all shocking that you'd find more inclusivity there.
A much more interesting study would be separating the gamers from the Gamers. Show me how people playing Splatoon and Animal Crossing compare to the neckbeards living in LoL and HoI4...