[michaelt]

It is indeed common!

But a keyboard flashed with malicious firmware becomes an undetectable keylogger, a USB rubber ducky, and a virus-laden USB stick all in one.

The concept that someone would want to reflash their keyboard firmware, but wants a sandbox because they don't trust the firmware programmer makes no sense.

[sagarm]

Hmm, that's probably somewhat fair. While you're using a protocol that's only intended to update the key map, it's probably not hardened against attacks.

Regardless, the real reason people use this is because it's incredibly convenient compared with using QMK and ZMK directly.