White paper: Vendor Kernels, Bugs and Stability

I'm not saying that messages are not useful for debugging. And for that exact reason it's always possible to enable a verbose boot.
But in the vast majority of cases nothing is "stuck" (didn't happen in a decade for me) and there would just be a blast of messages during a couple of seconds boot time that nobody reads.
Therefore, the default should be no kernel messages and also no systemd messages.

A kernel deprecation message would certainly go by unnoticed during the burst of messages.