He's not 'immune' to criticsm ever, it's just an issue with assigning shared blame, as well.
He was up and down all year, but he was outright bad after the Willie D incident in...Carolina? But it's also the first time in his career he's just flat out had a bad season, as well. Every goaltender in this league has at least one full on stinker. Everyone loves calling Price (not around here) The best in the league but he was three seasons of .905, .905, .900. Luongo has a .907 and now an .899 as well. Rinne's got a .910, .908, .902. Lundqvist's consistency was pretty legendary, but even he now has seasons of .910 and .907.
For all the **** Quick gets, he's got a .907 (rookie year), .902 (after back surgery, 2013, on his way to an epic playoffs), and now an ugly .888 in there (lowest save % season in I don't know how many years league wide as well, fwiw), yet it's just one year removed from a stellar .921, 33-win season. And for all the **** he gets, he put together more solid all-around seasons in a row than ANY of those guys previously mentioned, doing .918, .929, .902 (yuck), then going .915 .918 .918 .917 .921 all in a row without saying anything of his playoff heroics in several years. And that's without considering any of the 'depressed save percentage' effects of the low shot counter team, and also only relying on save percentage as a metric for 'good'. For as much criticism as he has received for being a mediocre regular season goalie, he's actually had less volatility than many of the widely-agreed-upon 'greats' of this era.
Guy has had an epic run and gets nothing but **** on constantly from just about everyone so you have to understand why it's maddening to hear it from inside, too, and why people are defensive about Quick.
There was a fantastic rundown in his trade article in The Athletic, basically talking about how people think he can bounceback and he should still have the high ceiling but that he needs to make adjustments both to this team as well as this era, i.e. we all know his aggressiveness gets him killed when he can't count on his defensemen to tie up the easy backdoor play, so his coaching and play needs to adjust to remain effective. Of course, there's also age and injury knocking at the door, so it's not simple, but an offseason of health and coaching will be good.