He does, but he's also a terrible pointer if we're trying to explain ancient tech is still relevant to writers. GRRM is such a celebrity that he's just riding out the "I'll write some more when I feel like it" money train, making him more of a hobbyist (with very good connections) compared to the vast majority of "there isn't enough time in a human life to write all the things I want to write" people in the fiction writing world.
Having something with very few bells and whistles lets you focus on your writing. Whether that's a "only works in fullscreen, you don't get to multitask" markdown editor, or a 1992 486 running word perfect on DOS basically makes no difference.
I know a fairly well-known children's author that continues to write using a typewriter out in an outbuilding on his farm. I imagine it's a very effective way to focus (for me, I'd have to make sure I didn't have my phone).
I have an electric typewriter I use occasionally. It makes for a very different feel than both typing on a computer and hand-writing. (The only reason I don't use it more often is that it has terrible ergonomics, even compared with today's flat keyboards.)
He's written 13 novels and lots of shorter works. He's not someone who's written very little.
I think his fundamental problem is that he's in a position that few writers end up in -- he became so popular that if he doesn't end the book well he will be hated and reviled by thousands of people on the internet. Most writers never end up in a position where if they let the public down, they will become hated figures.
Having something with very few bells and whistles lets you focus on your writing. Whether that's a "only works in fullscreen, you don't get to multitask" markdown editor, or a 1992 486 running word perfect on DOS basically makes no difference.