Why does everyone say that after d4 nf6 c4 d5 cxd5 is good

The idea of a truth is obsolet since Demokrit. Pardon. This leads too far away. Humans can't get "the truth".

And the idea, that win percentages on the level of the mass doesn't say anything, is very pejorative. It always depends on your questions to the data. Your question is esoteric. "Gehirnakrobatik" in an ivory tower.

1 game 2700+ vs. 2700+ says more than 100 games 2200 vs. 2200.
Games 2500 vs. 2200 say nothing at all: 2500 wins regardless of opening, regardless of color.
All those win percentages result not from the opening, but from later mistakes.
Your reasoning is like 100 years ago by Tarrasch arguing against the then neoromantic/hypermodern school of Nimzovich and others and their bad moves.

@tpr now was nimzovich correctt about the scandinavien being forever demolished? Maybe he was, whats the theory?

#43
Even Nimzovich was dogmatic.
Bottom line: it does not matter what you play: you do not lose games on move 1-2 but on move 10-20.