The linked spec in the original has all the hallmarks of "oh wait, maybe we do need...". It reads like what you get when someone has a poor idea of what 2D UI

The linked spec in the original has all the hallmarks of "oh wait, maybe we do need...". It reads like what you get when someone has a poor idea of what 2D UI requirements are (alignment, relative positioning, layout, out-of-band image delivery, updates, animation, ...) and then has to retroactively fit them in one by one. And then the mechanisms it has for doing so read like they are a poor fit for how you want to use them, requiring weird global bookkeeping/state, and sound like a nightmare without a proper API around it, abstracting it away. Aka reinventing all the lessons of 30 years of UI development from scratch. From what I remember sixel is _worse_ but that doesn't really change things.