Dealer's Responsibility?

Walking through a LV casino recently, I saw a player hit 3,6,A,A. Without thinking or breaking stride, I said to him, "You just hit a 21." He just shrugged (and stood on his 16). He lost the hand. I forgot the dealer's up card but I believe it was a stiff (and he probably should have doubled his original 9). Of course, before hitting his 21, he also hit his 20.
Of course, it is the player's responsibility to know the value of his own hand, but shouldn't the dealer have said something? There have been plenty of times where dealers have asked a player if they really wanted to do something that was let's say far different from basic strategy. This seemed to be particularly obnoxious by this dealer.

That was me using one of my self-styled cover plays.

your usual helpful answer. You are very consistent.

Recently I saw a lady split 2's against a dealers King. I wept.

I would definitely split if it was a match play coupon.

Why?

I am sitting at a table at the Trop, perhaps 15 years ago that just went from $10 to a $25, with a young lady grandfathered (or is it grandmothered) at $10, when this guy sits down and gets a $30,000 marker and they change it to a $100 table and grandfather both of us. They raised the limit because this guy might bet more than the 2 or 3,000 max they had on a $25 table.
Early on the guy gets 2,2 vs dealer A and splits and loses on both. He continues to play a terrible game of blackjack and takes another 30 grand marker out and loses everything in perhaps 30 minutes.

When he left, the young lady says to me, "how in the world can he do that?" Thinking she is talking about the 60 grand he dropped, I say something like it is all perspective and perhaps that money to him is the same as $100 to you.
Smart lady, she then says, "I understand that but just can not understand how he can play blackjack so badly."

And these same casinos will spend a small fortune to figure out if some green or even red chip counter is playing a winning game that could not even dent their profits made by bad players and go ahead and back them off???