Same as WebUSB - heaven forbid that a website can become more useful by flashing firmware to a device!!
The web is a platform. It will grow and mature into something we can't possibly imagine. It's OK for browsers to try new things to see what sticks.
I assume that Mozilla have done some research showing people like typing emoji but don't know how to use their system emoji picker. Even in an ultra-purist world where a browser does nothing other than render HTML (death to JS!!!) surely people will want to type into boxen and POST text somewhere?
Similarly, there were people who complained about forms and buttons at roughly the same time and, a few years later, img maps, frames, layers (okay, with good reason), and CSS.
They (or their spiritual heirs) always pop up on Firefox threads, for some reason. For those people, I want to point out that Lynx is right here and is as usable as it's ever been: https://github.com/ThomasDickey/lynx-snapshots
Useful for whom ? The CIA ?
The alternative would have been booting to Windows, downloading some dodgy .exe from an advert infested site, and running untrusted code which inexplicably required my admin password.
I'm pleased the Web is able to put a stop to nonsense like that.
Please respond to the strongest plausible interpretation of what someone says, not a weaker one that's easier to criticize.[1]