I wonder how much this is because of dumbing down, and how much it is because the market got larger. For example in the year 2002, The Sims was the highest selling game of all time, at ~6 million copies.

At the time, the perception of video games was still a hobby of sweaty nerds. Some years later the Wii launched, and it became really popular as a family console. It had some sports games, and I think it did a lot to get a foothold on a more general market. Games weren’t just for sweaty nerds anymore. Although even then, a lot of people didn’t play games.

Then at some point the marketing shifted. Games had broader stories, they tried for more mass-market appeal by selling cinematic experiences and whatnot (remember the awful QTE era of like the late-2000s early 2010s?)

At that point, I think gaming in general had broadened its appeal. A lot of people had consoles, PC hardware wasn’t prohibitively expensive, etc.

I don’t doubt that dumbing down games has had an effect, by making things simpler and flattening the learning curve you make it more accessible. That’s a given. But I also think gaming becoming a more generally accessible and socially acceptable past time was a big contributor.

Once smart phones came along the mobile game market exploded, and I think that’s still the biggest market segment, though it’s moved on from its original simple puzzle games into bigger experiences, some that even translate decently well over to other mediums.