well, I’ve been on a lot of core discord chat, and booting from SSD is not officially supported, as far as I understand it. That of course is the reason it is not mentioned in the doc you link to. The partition method is though.
So no, not kidding.
It can be done, there’s a whole thread on it: Installing Home Assistant on a RPi 4b 8GB with SSD boot
The simplicity of your method isn’t discussed there I am afraid? Seems somewhat more complicated than you suggest… 
btw, just started up in my new Argon case:
which is 20C cooler than before the case… wow.
this is without the fan blowing
