I think there is a difference in what their goal is. A player logs in the game to experience the implemented mechanics. A tester logs in to improve those mechanics.
You say “just remove the P”, well … that’s what CT already is. Just also with an NDA. But even so, the mentality of someone saying “hey, I’m willing to make your game better so I (and others) will enjoy it more later on” is different than someone logging into the test realm as “I’m here to play an Early Access version which might have some FPS loss or unstable servers, but as long as I’m having fun now, I don’t care.” The current CT/NDA format probably filters out a lot of the second category, so the limited resources of a CT-server support team can be utilized more efficiently. And that’s what it comes down to: using their limited resources as efficiently as possible. Larger companies like ActiBlizz or GGG simply have a far lower threshold for efficiency, so they might be able to do CT, PTR & EA all at once.
As for how many people are needed to optimize CT value for LE … I don’t have numbers on that, but I assume it’s something EHG looks at on a monthly basis. (Or at least they should)
The argument here is that turning CT into PTR only gets you more of the first thing, which can drown out the latter, as you only have X people reading the forums within the company.
I never said intentionally making bad guides. But you don’t know on patch day if a guide is purely slapped together based on nodes, or if it’s tried & tested. Regardless, guide creators might not be a good argument to bring into this, let’s stick to people neither creating guides, nor the ones that are gonna google one on patch day anyway.
What data are collecting that you can’t get from the server directly?
You could collect offline data, but as it’s open to exploits/cheats, it’s not reliable data anyways.