It's not at all but we live in an era of short termism and hysteria, with no room for balance or nuance. It seems you either have to hate the bloke and everything about him and think he's the worse thing ever to happen to this club, or you have to absolutely love him and everything he stands for and back everything he does. You aren't allowed to sit in the middle anymore.
You hear some of abuse he gets off his own fans, and you wouldn't expect right-thinking folk to be like that towards their worst enemy, let alone a guy who's just trying to do a job the best he can. But logic goes out the window with football fans.

He is unfortunate is some respects because he's followed some managers who have worked wonders here and done jobs that have perhaps never been given the credit they deserve(d), and in comparison it looks like he's failing. He's also unfortunate in that he's joined a club with expectations that are so high, based on the number of trophies won over the past 15 years, which doesn't account for the fact that in the cold light of day, when you look at it from the outside with a disconnected perspective, we are currently pretty much performing at par, for various reasons. I think a lot of fans are still stuck in the days of when we were by far the biggest spenders in the League and you had nowhere near the level of competition at the top as what there is now, especially given how drastically different our spending/transfer policy is from the first half of the Roman era, so you can't judge him the same way we judged Scolari etc. back in those days.
When you consider that many of his critics also criticised Mourinho, Conte, Ancelotti, I do think our support has got to the stage where they will literally never be satisfied or allowing of anything less than perfection anymore. It's one thing having high expectations and high standards, but when they're not necessarily aligned with realism, then these types of fans are never going to be happy.