I think there is some confusion and potential for misinformation here. SSH in key-only mode (common configuration) protects you from this problem, because it never accepts or even attempts any passwords at all, regardless of length. SSH in password-allowed mode with at least one user who might be a key-only USER by merit of having a password hash of "*" (not a valid password hash) is a prerequisite for this. That is a very different and very common thing, as most systems come with at least one key-only user by default. But gaining access to that user with an incorrect, invalid password still requires having passwords enabled at all.

To be clear: Password access enabled is a prerequisite, and by extension, password access disabled (key-only) prevents this.

The website you linked clearly defines that all of these conditions must be true for you to be vulnerable, and as far as I can tell, it is exactly correct:

is your sshd running on musl? (alpine, openwrt, buildroot, yocto)
is it not using pam? alpine's openssh-server doesn't by default, or maybe you set UsePAM no
are password logins still on? they are by default
is there an account with just * as its password? key-only users, ldap users, root on alpine
and some other account with a real password?

then that * account takes any password between 257 and 1024 characters

The * account which they suggest potentially being "key only" is the prerequisite you are talking about, but having SSH itself key-only (which is best practice anyway) prevents the attack entirely.