Consider this wording. It also uses “good practice”.
« It is good practice to limit the number of superuser roles that exist in a cluster to exactly one: the inevitable bootstrap superuser. This recognizes the fact that, once the initial configuration of a cluster has been done immediately after its creation (which configuration is done while still in self-imposed single-user mode), there are then very few, and infrequent, tasks that require the power of the superuser role. »
Nobody supports it!
I went back through the thread and don't anywhere when you made the above statement, correct me if I am wrong. In that case there was nothing to support or not support until now. What people where responding to the title of the thread:
"Seeking practice recommendation: is there ever a use case to have two or more superusers?"
That is a different ask.
I didn't mean to say that I'd already written the sentence that starts "It is good practice to limit the number of superuser roles that exist in a cluster...". Sorry if I gave that impression. It was just a strawman version of what I practice recommendation might look like that used the same general wording style as the one about "a role that has the CREATEDB and CREATEROLE".
