If you even know what an ESP32 is, you can get a browser extension to use WebUSB. Very few users need this feature built-in, let alone enabled by default.
Maybe hasn't been done, but I agree with some of the other comments around here that if this were truly important, someone would've done it. Or at least if a browser is going to support it, it should only be enabled via some hidden dev setting.
> if this were truly important, someone would've done it
That's basically a variant of the efficient market hypothesis for open source software. I highly doubt it's accurate, for various reasons.
Things that people retrospectively consider absolutely essential and a no-brainer to prioritize get shipped years after the initial release of some software all the time.
In this case, it's probably because the alternatives are good enough, even if it's just that Firefox users open Chrome in specific instances where they want to connect to special hardware.
