I'm an advocate for creating codes to solve problems. I've literally written a terminal emulator with that in mind: https://github.com/lmorg/ttyphoon -- there I defined codes for graphical features like interactive tables and inlining AI elements in non-intrusive ways.

My qualm isn't with defining new escape sequences. It's:

1. calling Kitty's specific double height/width escape sequences "modern" when it's using the same 1970s principles as the original double height/width codes.

2. Kitty reinventing the wheel here when it adds no benefit to the original codes.

It's the same reason I get annoyed that there are 4+ different proprietary codes for inlining images.

All of this continual reinvention of the same ideas just creates more problems than it solves.