> is a bit of a junior- to mid-level engineer tell in my eyes
There is absolutely no reason for Discord—a chat application—to run everything a browser does. Why do I need to play videos in the chat application? Why do individual avatars and even tags have to run custom shaders? It's called scope creep.
> a11y, IME, RTL
All of this can be done at the platform level. Win32 did this three decades ago. Comes with entire language packs.
> so you add a scripting layer, maybe integrate a little Lua VM or something that lets you execute JavaScript
See above: scope creep; features for features' sake.
> Why do I need to play videos in the chat application?
You know exactly that the moment that Discord launches a new version that no longer plays videos, people will whine about it.
> All of this can be done at the platform level. Win32 did this three decades ago.
Yeah, but they're porting to Rust and GPUI and not that.