NO_COLOR exists, and is fairly widely supported. TERM=dumb to disable colour was always a hack at best because this also disables other things like "clear line" and generally leads to weird output.
> It's a Chesterton's fence.
It's not. The world has changed. Everyone uses \x1b[1m to make text bold today but in the past there were a few dozen ways from different vendors of (hardware) terminals to make text bold. But this situation no longer exists. Like I already said: you still need it for some things – there's a reason I compiled a "safe terminal escape code" list. But for many things you don't.