People don't need an extra supply-chain failure mode to consider, and CVE proved these dongles are mostly security theater. Likewise, the recent Coinkite user key prediction breach certainly wasn't cool for folks that lost their holdings. =3
Storing the secret on a hardware token will most certainly help with not committing into source control.
> these dongles are mostly security theater
...as opposed to? What's your criteria for "non-security-theater"?
Wrong cve and a side channel attack doesn't mean these dongles are useless. It would have stopped the firefox team's ai from commiting their subkey ;)