> For password-protected keys, that means that the user must enter the password to decrypt the private key before the ssh client can use it to authenticate with the server. Since many users like key-based authentication because it doesn't require passwords, this extra level of key security can be annoying and often gets omitted.
Wrong. These users neither omit the passphrase nor are annoyed, because they simply use ssh-agent. Like this, they have to type the passphrase only once at login. And as a bonus, ssh-agent automagically manages multiple identities.
The only major omission I can see here is: not mentioning ssh-agent in the main article. Hard to believe.