"I don't think this is good advice to the kinds of people who don't know if they should be running 14.4 or 15.0."

You don't need to wonder about this because FreeBSD has an official, documented position on this topic[1]:

"... include work in progress, experimental changes and transitional mechanisms that may or may not be present in the next official release ..."

"... whether or not FreeBSD-CURRENT sources bring disaster or greatly desired functionality can literally be a matter of which part of any given 24 hour period you grabbed them in!"

"(is not) In any way ``officially supported'' by us."

[1] https://docs-archive.freebsd.org/doc/4.4-RELEASE/usr/share/d...