This was asked a bunch of times during the 2024 playtest, and all I can say is that I don't buy it. there were some changes that would have impacted play as a whole, but we did not have a whole game to test. Most of thsoe were pulled back on.In the case of 5.5, given that the core mechanics were largely unchanged, and what was being changed were modifications to classes, monster, spells and the like, why wouldn’t piecemeal work? It’s not like the mechanics were unfamiliar to anyone. Perhaps the biggest change were the weapon properties as a new subsystem within the game, but the game was not completely rebuilt from the ground up.
I will reiterate my position just to make it clear: I don't think that the fandom willing to answer surveys are necessarily good at providing design insight, and I don't think that testing games less than holistically does much good.