Good grief at no point did I suggest actually taking peoples XP away from them I simply suggested using it as a resource ingame like a currency. The games grind is already long; no need to make it longer.
This might be a solution to that. Add another column behind the XP score labeled as XP Spent.
You keep all the XP you gain from the match as per usual, but you can’t spend more then you’ve earned.
So for example you’ve got 1500xp you can spawn 3 tanks or 2 planes and as you keep playing and doing stuff as you get more. Heck maybe you go on high kill streaks in the tanks or planes and you make enough XP you’ll be able to spawn another one again once a slot opens up.
Perhaps they could try an event or something where they take the point concept and try it out on regular tanks and planes. It would be a good way to separately from the main game test out the concept of loosening restriction on vehicle limits but putting in a currency to get them.
(*cough, Warthunder)