Yeah, I might be able to buy that if he hadn't treated Barclay, Lavelle and Shelby the same way. Only reason Jellico didn't get the same treatment was because he had the rank to not have to put up with his hostility towards outsiders.
Lavelle I don't quite remember and am not going to look it up right now, I'll deal with Shelby first:
Shelby was a guest on the ship during a special assignment but acted as if she was already in Riker's job. During their first major confrontation Shelby takes two of an Enterprise senior officer down to a potentially dangerous planet without asking permission first from the Away Team leader (Riker.) In their second major encounter Shelby, again, skirts the command structure and dances around Riker to take a suggestion directly to Picard. She needed to be smacked down for the presumptive behavior she was acting with, in assuming Riker was on his way out and that she was the new First Officer on the ship.
Barclay? Really, come on, can you blame Riker or even Geordi for that matter on how they treated him? Show up for work late a few times and occasionally piss off during your shift a few times to play video games and see how well your bosses treat you.
Barclay was another case of the crew dealing with someone that was a problem, like Ro (though less severely.) Here they are on the Enterprise, the pride of Starfleet, and they're dealing with a stammering guy who can't even manage to show up on time for his shift. Riker may have been actine a tad-bit harsh towards him but in the indication I got in the episode is that this had been going on for quite some time and and was just now reaching its breaking point with Riker. He was getting fed up with, as he says, always seeing Barclay's name on report.
Now, how Picard handles the situation was well done, I feel and he does nicely smack down Geordi (not so much Riker who gets very assish by barging in on the Holodeck where, frankly, he could've encountered anything) and get things straightened out but, still, Riker was dealing with a bit of a troublemaker. A slightly insubordinate officer or at least someone with little regard for the rules. (Though not defiantly so like Ro, just someone who probably need to be medicated with some mood-stabilizing drugs or something as their emotional issues were causing them to ignore or disregard the rules. I mean he's about to go on duty and he goes dicking around in the holodeck and doesn't even set a notice with the computer on when he needs to leave?!)
Riker has plenty of times when he's being an ass and he can be an ass. But I don't think this was a systemic problem with the Enterprise crew playing "favorites" with one another. (It may seem that way, however, since we have almost no secondary crew members like DS9 did and when one IS introduced it's done to cause conflict in the story so by the rules of drama the crew HAS to act a certain way against these "outside characters.")
... Was Lavelle the Riker-like kid in "Lower Decks?" I vaguely recall, but I'd chalk that up to Riker simply being hard on the junior officer for training purposes and perhaps even seeing a bit of himself in the kid so being hard on him for the sake of "straightening himself out vicariously through Lavelle." Riker does seem somewhat civil towards him during their encounter in Ten-Forward when presumably both are off duty where, presumably, the command structure no longer applies.
Riker was an ass. With Barclay, Lavelle and to some degree even Shelby perhaps too much so. But those also were all situations where there's some justification there and some blame can be placed on the other party (except in the case of Lavelle where it was just a consequence of his rank.)
But when it came to Ro? Again, she was the very definition of a trouble maker who was handed a prestigious assignment. She NEEDED to be smacked down and smacked down HARD for her previous actions and as I said one of the ways to do that is to apply the rules strictly.