Its not so much the person having more pretend authority, as it is the position having more pretend authority based on who holds it. What I am suggesting is that from a storyline standpoint, it is easier to believe Stephanie or Shane McMahon as a key authority figure in the WWE, because they really are authority figures. With Eric Bischoff, we know that he ran WCW for a long time prior to becoming the GM on RAW, he had "street cred" as a GM, as an authority figure. Paul Heyman, as ECW GM, had street cred, based on his history as the actual owner of the original ECW.
Other performers that acted in an "authority role", whether its a show GM, commissioner, "WWF/E President", or whatever they called it, performers like Vickie Guerrero, Sgt. Slaughter, Armando Estrada, Debra, etc simply don't get the same respect, because they aren't necessarily an appropriate fit for the position.
With Stephanie McMahon, her on-air role as Smackdown GM was more believable because of who she is in real life. Eric Bischoff worked as RAW GM, because of who he is in real life. Paul Heyman was believable as ECW GM, because of who he is in real life. Just because the position is fictional doesn't mean that a wrestler/diva/announcer is right for it. Lou Ferrigno was appropriate as theIncredible Hulk in the old TV show, but he wouldn't have been appropriate as Dr. Banner. Bill Bixby was an appropriate Dr. Banner, but would not have been appropriate as the Incredible Hulk. Both are completely fictional characters, just like a WWE GM, but, also like the WWE GM positions, they can be miscast. Vickie Guerrero is a complete miscast in my opinion. No offense to her, but she only has a job because her husband died. She was never a wrestler, never a diva, never an announcer, wasn't a long time WWE employee, never ran a wrestling promotion, she was simply Eddie Guerrero's widow. Stephanie McMahon however, had been a wrestler, not a very good one, but she did wrestle, she had made numerous appearances on WWF/E television prior, is the owner's daughter, and as such she actually does have real authority in the WWE, making her pretend authority easier to believe, and is someday going to co-own the WWE with her husband and brother. That gives her far more credibility as a storyline GM than Vickie Guerrero. I can certainly understand if she isn't one of your favorite people, but, I cannot celebrate her being gone as GM for five years, when her being gone has led to Vickie Guerrero, who is absolutely horrible.