As we stated on our forum:

"We are not willing to sell vehicles on Auction and via trophies/marketplace.

First of all - we do not like the idea of making our hard work available only for a few. That is in a way not bad for customization - as customization is a way to make you unique in presentation, but not in terms of gameplay. But not good for vehicles. We were making several time limited options to purchase vehicles in several cases for different reasons, but in general that is not we do like.
We prefer to see our vehicle be available for anyone it anytime (or at least at certain times). FOMO is real thing that will work in any limited options (events, discounts, etc), but not the thing on what you can make long-time relationship. And amount of vehicles in War Thunder requires long-time relationship, you know what I mean, I guess. That’s why we reconsider research times and prices each year and that’s why we are returning some rare vehicles like E100 or Maus (which we have and do not want to see much on the game cause of known reasons) to the game. So even such vehicles we do not want to put in Auction (and never wanted of it).

Another reason (not the main) why we are not going to put vehicles in Auction is that purchase in GJN are the best for content creators revenue share (or even the only option) , but they also not available for console players, which is also very unpleasant and obviously not we are happy about.

The reason of ‘refusal to deny’ is that are very old discussions (and as in most cases - come from players suggestions) is to have some kind of option to get vehicle (for limited time or perpetual) when you buy a skin (cause otherwise if some player want a skin but do not have vehicle - there is not much sense for him to buy a skin until he get the vehicle). We are not planning that anytime soon, never even have detailed concept (there are some complications in terms of research and game progression system). This thing (if would be ever made) would provide something like ‘oh, now they sell vehicles via Auction’, ofc technically it would be that, but obviously that would give an EXTRA way to get the same vehicle can be purchased via gaijin store\gold(premium)\ or regular research tree. Again, we are not even have a detailed suggestion, do not plan it. But this is an option of how to provide more ways for players to get the same vehicle, not a way to get extra money by replacing current ways to get vehicles.

Most developers are scared of how players can percept any changes in progression, store and everything. The Auction was made several years ago, being proposed before Marketplace, but as most are afraid of (some?) players reactions it hadn’t been released.
I personally think that Auction is naturally fit the idea of selling pieces of art (which skins are) so forced to give it a try. May be I’m wrong and no one like it. Or may be we need to change details of how it made (from amount of items which are on Auction to currency of it).

Hope I’ve addressed your concerns. Thanks."