They started in 2022. Do you think they should have started in 2020? Of course, they weren't going to show us the early iterations of every single rule, so they would have had to start internal playtesting in 2019, 2018?
Sure, that sounds nice, it sounds like "oh, well clearly they should have developed it starting 6 years ago, instead of 4 years ago." But... We do know that they were trying ideas in other unearthed arcana's during that time. We know they were changing things in the monster books, so internally they WERE doing that, weren't they? And ultimately, you can't escape the fact that there are simply practical limits on how much a public playtest can do. You can't release the entire book to be peer edited by the community, for free, multiple times. It just isn't reasonable.
I can never fully get over the arrogance displayed when discussing the playtest feedback. Every single person from EnWorld combined is a drop in the bucket to the responses they got back. And we, as the EnWorld community didn't agree on half the material and each of us generally came up with three different fixes.
Your preferred version of something didn't show up, so clearly it was discarded without even considering it, because of course it is impossible that they were looking at two different versions of the rules and the one you thought broke things, they found broke fewer things than the other version. Or that the level of how it broke things was acceptable compared to other, more urgent design goals. Or that they observed the data and saw that only 0.03% of respondents thought it was an issue, so decided it likely wasn't going to become a wide spread problem.
Despite having no idea what their considerations were, what their turn around was, what the rest of the feedback was, what their options and perspectives were... clearly they just didn't bother with the objectively correct versions presented to them by the minds of EnWorld.
Does their process need improved? Maybe. But before I started demanding that? I would like to know what their process is in its totality.