The only pay to win factor is that if there's an operation going (community made maps which are accessed by paying 6 dollars for a list of tasks on those maps such as get 10 headshots with this gun or whatever) and it only gives you bonus XP which does effectively nothing. The only gameplay thing that xp is used for is that at level 3 you get access to competitive which is where the meat of the game is, afterwards its basically meaningless points.
