XP system is extremely unbalanced

Whenever I play Breakthrough, half of the players in the game have Casper with proxy mines equipped to get the most XP because that's literally the best way to gain XP.

50 XP per spot assist is not too much, the issue is that other XP sources simply aren't enough. Let's take healing for example: 5XP per person healed? Wasn't it 1XP per HEALTH PONT healed?

The ammo box is also never used to resupply teammates, I've barely seen anyone use them. Is it because people prefer a rocket launcher over an ammo box? Probably, but keep in mind that it's 5XP per ally resupplied, and a vehicle kill with the rocket is around 300-ish XP. I usually play as a medic, so I really want to keep playing Falck, but I see myself forced to play Casper to level up and get the guns/ gear I want. I don't mind the grind, but this XP system is so unrewarding for team play, which is supposed to be one of the CORE aspects of the game... I want my actions to feel rewarding. Why would I heal an ally at 1HP for 5XP when I can wait until they die then revive them for 50XP? There's clearly an issue here