From a monetary point playing blackjack at all in a casino is irrational, even if you could bring in a computer to calculate the odds and track all the cards played (perfect card counting not the estimation techniques most humans have to use) most casinos have set up their tables that perfect play looses money unless you have a group of people sitting out who are signaled to join in when a table is hot and max bet (there is a reason blackjack tables have a min bet and a max bet and reshuffle their comically large decks so frequently) and if you do that you will be 'politely' asked to leave and never return.

I'd argue that it is irrational to call someone out for sub-optimal play, its pretty easy to show that if blackjack was played with players hiding their cards until after the hand that the hit/stand wouldn't effect the odds of following play, meaning that what is aggravating is that because you have more information you can see when a mistake by the player ahead of you 'cost' you the opportunity to win (even though the same mistake had an equal chance of creating the same opportunity to win). So it would be no more reasonable than getting angry at your friend for winning a draw when you remember that he bought his ticket right before you so if he hadn't bought the ticket yours would have won.

For a small example of how this hit actually helps you (though so marginally its not really worth anything in a real blackjack example) consider the dealer only has 2 cards, and you need one of them to win, if he stands you hit and have a 50% chance of winning.

If he hits we have 2 equally likely scenarios: He gets the card and you lose, He doesn't get the card and you win.

Technically at a blackjack table the latter scenario (where he hits) is better for you as if he doesn't get the card you would double down, but you are never gonna have just 2 cards left for the dealer so the advantage of the hit is moot.

So to reiterate, next time you see someone make a mistake and take an extra card, thank them, they took one for the team so you have more information about what the next card will be than you would if they didn't :)