So you dont think an open playtest would have revealed what people thought of it?
People literally cheered when WotC told them Vancian casting was being removed.
"What people think of it" was
wildly variable. People got HUGELY HUGELY mad about
Or thst the math didnt actually work and they had to rewrite the MM in effect?
Such a playtest would have
revealed such a problem, yes, so then it
wouldn't be one. That's...literally the point of real playtesting, as opposed to performative playtesting. It's literally about
testing things to make sure they work, and if they don't,
fix it.
Can't see any of those possibilities cropping up?
The first one is irrelevant, and the second is literally the point of the exercise, so....I mean the answer is too complicated to be a one-word "yes" or "no".
But if I must answer as you've specifically presented it? No, I cannot see those possibilities
in the way you described. Instead, I see them as follows:
1. During the playtest, nothing meaningful would be learned about presentation, because players expect pretty basic presentation at this point. No one complained that the "D&D Next" docs were black-and-white word docs in PDF form. So that part's just outright gone. Second, it is--or should be--expected that ideas will grow and evolve, and that feedback will be factored in. Thus, the only real element that people could have "revealed what [they] thought of it" would be...pretty much the exact things we already saw. In other words,
I don't see how anything meaningful would change, other than the designers getting more direct/specific/usable feedback because of better survey design. That's....all good, as far as I can tell!
2. Fixing math errors like the thing you describe is one of the greatest
benefits of doing what I've described. Most of the math errors in 5e, for example, come from not testing things.
Not being rigorous.
Not having well-constructed surveys, nor conducting robust simulations, nor proper statistical analysis. And the exact same thing is true of 4e. The math errors you love to crow about so much
would never have happened, because this testing process would catch them and fix them
before publication. So....yes I foresee that happening and it is a directly good thing.
Hence, the things you describe are either utterly irrelevant.....or precisely part of the plan.