I don't know. I used emacs for a solid year (in evil mode admittedly), and my configuration kept breaking with new updates. I spent more time fiddling with my config files than being productive. I love lisp and the idea of emacs. But when I started using vscode, my productivity immediately jumped. Emacs also suffers from latency spikes, even worse than vscode does. I want Emacs, but with the speed of Rust, and the polish of vscode.
I don't think that's what he is saying. He is saying that Emacs once ruled supreme because it was the only option. Now that IDE's have caught up, it's in the lead by only a little.
I'd say still by a lot, but yeah, IDEs have advanced in the last 20+ years (and one of the main advantages of something like VScode or IntelliJ is that it does a lot "out of the box" and it's pretty discoverable).