“Professional” in this context refers to being paid for your work while you work on it, rather than making a game unpaid in hopes of receiving recompence from sales once said game is released. (“Indie publishers” are a thing, to be sure—but then that opens the whole can of worms of, are you “truly indie” if you have a publisher?)

Semantics aside, the point is, at one point in time, it was very good and healthy for the medium to have a vibrant AAA (and AA) video games industry. You're generally not going to see indies pushing the technical frontier forward, practically by definition. Things were never perfect, but they were better than they are today. Nowadays, it's basically impossible for someone to get a salaried position making video games.

Which is a bummer, because I grew up thinking that would be definitely where I was going to end up in terms of my career—having some salaried position somewhere, making games with people with different skillsets and areas of expertise than my own, learning from my seniors, having a sense of comradery with the people I worked with, becoming a better game developer. That ship has sadly sailed (or sunk)—it doesn't seem likely that we will have an industry like that again anytime soon.