Ondergetekende

Security through obscurity is a very valid way to secure something. It shouldn't be the only way of securing something, but it can be a valid additional layer.

The knock sequence is a secret, just like a password. It may not be a particularly strong secret, but is is strong enough to keep out casual attackers. You'll still need additional security, but sshd is well equipped to provide that.

To be fair, that's true for most US headlines these days:

• coup-leader repliblican favorite for president.
• Pro-life movement causes infant and maternal mortality to rise.
• Debt ceiling negotiations will start about 4 weeks before deadline.