I think people watching the mob from the outside get hung up more on titles..."whos the boss? whos the underboss" what period did they control?... a lot more than the actual participants do.

It helps us keep everything neat and orderly for our little charts.
The reality is someone like Crea can give orders as he needs to, still get his envelopes and have plausible deniability if ever at trial of being "boss". It would seem to me to be the much smarter and more prudent technique to use when running a crime family. Create confusion. worked for the Genovese for decades. Those that need to know will know.
Only someone with a Gotti like ego would NEED the title but guys like that only come a long once in a generation and usually don't make it to the top...history shows big egos are usually cut down long before they get there.