Then that's too bad for anyone who tries to use non-standard shells. It's one thing to violate a vague, rarely used standard. It's quite another to violate what is most likely the most broadly supported standard on *nix systems.

Dash is Debian's default non-interactive shell, and it isn't POSIX compliant. The only way to get POSIX compliance on Debian is to switch to a different shell (e.g. bash).

I checked your link but I don't quite get it. Is status=0 supposed to be a check rather than an assignment?

Either way, it doesn't have that behavior like that for me on Debian: it behaves the same as bash. This is in dash:

    $ command -v whoami
    /usr/bin/whoami
    $ echo $?
    0
    $ command -v echo
    echo
    $ echo $?
    0
    $ command -v nonexistent
    $ echo $?
    127

So that is with both a proper command (whoami), a shell built-in (echo), and neither (nonexistent). It's all as I would expect from a shell.

Bash does exactly the same, although dash chooses 127 as exit status and bash chooses 1 but they're both nonzero (thus error statuses).