Kind of comical. So if you support a club then you can't ever voice displeasure?
Nobody said that. A player shouldn't be booed for being taken off by the manager for tactical reasons. In this case he wasn't playing poorly, or making mistakes and was being taken off, Emery made a tactical switch and he decided to take him off. The second part, he's their captain. If he's not good enough, the abuse shouldn't be shown towards him, he's not being picked to play. Regardless of how much money he makes, that doesn't change your ability on the pitch. It's not as if he doesn't put in the effort, and doesn't care about the club he plays for, he's just not good enough and the Arsenal fans are pissed. But to boo him for being subbed off, is inexcusable however you want to look at it.
These players hear worse every single away game and if being boo'd was going to break their spirit then they would never have made it to this level in the first place.
Of course they hear worse, but that doesn't excuse the behavior. Abuse by other fans or individual fans while they're playing doesn't compare to the entire stadium booing you for being taken off at your own ground. The two aren't equal.
If Donald Trump or Alexander Boris de Pfeffel Johnson were to walk by I'd boo them and if I was questioned why I'd tell them to fuck off to, they're public figures and that's just part of being a public figure.
Comparing apples and oranges. Donald Trump and Alexander Boris de Pfeffel Johnson aren't just bad at their jobs, that's not why you would be booing them alone, their character,their behavior,their actions,their bigotry,racism,etc.. is why you're booing them. So unless Xhaka displayed all of that, on the pitch, did something so abrasive and disrespectful, then his ability alone isn't a reason why you would boo him. His effort and professionalism is certainly not the issue.
So a poor example. We've had some abysmal players [Salif Diao for instance] but it's shitehouse behavior to boo a player because they aren't good enough. Lucas was wrongly booed by our supporters, and while they have ''the freedom'' to do so, it doesn't make them less of absolute bellends and tw@ts for doing so.
There's only a set of circumstances that individual players should be booed by their own fans [El Hadj Diouf for instance spitting on a fan] and this isn't one of them.