Your point would be valid if and only if I could not point to the other 11 QBs in the playoffs and say "they also had at least one awful half". EVERY single one of them I can say that about. We watch all 12 QBs in the playoffs have awful halves (not sure what the correct plural is here) and in some cases multiple. The difference is not having a defense be historically bad.
I know you want some massively high scoring game but playoff games are typically not that. Just to demonstrate briefly what I mean by that: 4 wild card games, 4 divisional round games, 2 championship games, and a Super Bowl gives 11 total games and with 2 teams playing there are 22 teams who can score points in those 4 quarters (hoping I explained this well). Of those 22 the Cowboys loss was the 4th most points scored in the playoffs only passed by the Packers 48, Texans 45 (Browns were just horrid on all fronts), and 49ers 34 in NFC Championship game. This is not to say the offense was great but merely to show that playoff tend to be lower scoring and you do not typically see 40 point games like what you were saying was the "standard" for a not horrible game.
Now you are just rambling and making points that aren't really applicable to the discussion.
I don't care about the other 11 QBs. I care about ours. These are the realities. He's struggled to be consistent in big games over his career. He's struggled in playoff games at times. Heading into that Packers game, there were A LOT of questions not from Cowboys fans but from media/analysts about what kind of Dak we'd get and would he take that next step.
He did not. He struggled in the first half (along with the defense). He had two interceptions that led to two TDs - one on a short field and one on a return for a TD. He was a major factor in that game being 27-0. with a couple minutes left on the clock in the first half.
It's not about me wanting it to be high scoring, whatever that means. The point was that if Dak went out there and played great and the defense just got roasted, you'd have a fair point about defending Dak. But Dak didn't have a great game. He had an inconsistent, at best, game and was so dreadful in the first half that the Cowboys were down by 27 points at one point. Again, that's just reality. It's not a spin, it's not made up, it's not inaccurate. It's the reality. Dak played poorly, the defense played poorly, Dallas was down 27-0.
And then with all this going on, you put this in the context of Dak and his overall playoff track record. It's not great. It's pretty inconsistent where he looks great one week - take TB two years ago - and then the next week looks like a different QB. He played like a MVP for much of 2023 and then the playoffs start and he looks like a backup for a half.