DNSSEC lets you delegate a subtree in the namespace to a given public key. You can hardcode your DNSSEC signing key for clients too.
Don't get me started on how badly VPN PKI is handled....
The WebPKI and DNSSEC run global PKIs because they routinely introduce untrusting strangers to each other. That's precisely not the SSH problem. Anything you do to bring up a new physical (or virtual) involves installing trust anchors on it; if you're in that position already, it actually harms security to have it trust a global public PKI.
The arguments for things like SSHFP and SSH-via-DNSSEC are really telling. It's like arguing that code signing certificates should be in the DNS PKI.
Providing global PKI and enabling end-to-end authentication by default for all clients and protocols certainly would make the internet a safer place.
Do you hardcode Github and AWS keys in your SSH config? Do you think it would be beneficial to global security if that happened automatically?
Further, I haven't "moved on to another argument". Can you answer the question I just asked? If I have an existing internal PKI for my fleet, what security value is a trust relationship with DNSSEC adding? Please try to be specific, because I'm having trouble coming up with any value at all.