Thank you for the well thought out response.
I would be very surprised if you were wrong and I'm sure that's a major contributing factor (see the M60 for example).
I certainly don't have the in-depth game knowledge that a number of posters here do, especially with regards to all the important tank stats. But can you really look at all of these "overperforming" tanks and tell me they're strictly because of good players buying them? I don't even have to be good at the game to tell you it's pretty clear the Pz-II J is unbalanced as fuck. Selling it in that state is just ridiculous. Had it been implemented as any other premium (see the SU-76i) it would have been immediately removed from store. Instead in spite of how blatantly OP it was, it was bundled with a 30K Gold Package and given away for free. I get it, it's Tier 3, but still dude, that so clearly Pay2Win. The tank is knowingly unbalanced let allowed to exist on the server in limited numbers. Specifically so a few "haves" can farm a few "have nots."
What's the logic behind removing a tank like the SU-76i from the store because it was overperforming, but not actually rebalance the tank? If you buy something OP you get to keep something OP? This is from WG's mouth, not mine. You can tell me the SU-76i isn't really OP at all (like I'm sure you'll disagree with any number of other Premium tanks being OP) and yet the reality is WG felt it was unbalanced enough to remove from the store with no plans to rebalance or reintroduce it.
The same can be said about the Type 59. Hopefully you'll trust me enough to believe me when I say I honestly don't find the tank itself to be OP. It's definitely not an 'I Win' button by any stretch. But it's still, arguably, one of the best Tier 8 Mediums in the game. It has Pref MM on top of it, a clear deal sealer, imho.
I simply cited the Type 59 as an example of a tank (specifically the HD turret change) the WG is apparently reluctant to balance out of fear of upsetting owners of said tanks.
Overall my thoughts on the subject are pretty simple:
I think Wargaming shouldn't be limiting the availability of tanks they deem to be OP (or overperforming); they should be balancing them.
Personally, I want all tanks to be available at all times. I'm totally cool with a few tanks that only come on sale during special occasions and whatever else, but they should be an annual thing. Not a "this tank is never coming back to the store".
I don't understand how the expectation to buy and keep something that's considered OP by the company itself can't be construed as Pay2Win.