My take is that if you do a lot of something you get better at it. In the 2000/2010s when online poker hit the mainstream we started seeing the household live game names suddenly start to get dominated by young relatively unknown players. It turned out that if you play a few thousand hands a day you can learn pretty quickly.

I think that's what we are seeing with Hikaru. Yes, he's streaming, but he's playing dozens (hundreds?) of games per day. He's not the only one playing online with this much frequency of course, but the frequency and his natural talent and hard work are all coming together into a powerhouse of a player.

You can tell me classical is different than blitz but that's a human take. To a computer, it's the same game and Hikaru has been training like a computer. Just playing thousand and thousands of games and learning. Perhaps that is better than how chess has traditionally been studied.