I'm not familiar with FIFA, but in Counter Strike and Overwatch, this claim that "players buy an advantage with real money" is completely false, as lootbox rewards are 100% cosmetic.
Now, counter strike's skin system allows skins to be resold, so I still understand the gambling claim, as some people may drop money on boxes, hoping for a greater return. But overwatch skins are not transferable in any way. Overwatch also gives plenty of opportunity to earn lootboxes without purchase
The reality of the situation is that game development costs continue to increase, and when you add inflation on top of that, continuing to charge $60 for a game really isn't enough. So unless you want to pay $80+ for a game, developers need to find a way to pull in additional money.