While I agree to an extent, I really don't think there is a big deal with pointing out referee mistakes in the moments after defeat. The most successful clubs in CL of the last half dozen years, Madrid, Barcelona, and Bayern, cry foul every time a ref decision goes against them (and they lose because of it), and have been doing so for years.
It's when those complaints lead to years of talk about conspiracies and fixed matches and UEFA-ordered favouritism that it becomes a severe mentality problem like you see with clubs like Inter, Roma, Napoli.
When bad referee performances affect the club, I want the management to say so, and to say it's unacceptable in the immediacy. And then I want them to move on from it. Which is what happened against Bayern Munich in 2016 with the Morata disallowed goal when he was a whole metre onside. The management spoke about it the day after and then didn't bring it up again. And aside from Gigi (for obvious reasons), that's what happened with Allegri and the management after Madrid. Within a day or two no one was talking about it.