I hate to break it to you but if the developer/publisher advertised it with full progression we should get 100% of the XP even from bots and not 0.
I don't even understand why you find it unfair, why do you even care? If you want to grind weapons and attachments in regular multiplayer, you can do that, but if someone doesn't want that, they have every right to do it in another way without punishment. As long as they don't break any rules, obviously.
Playing against bots is no exploit or bug abuse or anything else, it's just a feature that is in the game, and it's not something like pay to progress or pay to win which you could argue as "unfair".
You can't argue that you want to grind weapons through multiplayer if you force everyone to you likewise. Everyone can decide for themselves if they want to do it like that or not. And if that's unfair to you, then that is your problem and not theirs.
If you want to enjoy regular progression fine, do as you please but don't expect everyone to do the same, especially if there are legitimate alternatives.
I don't get why you are so eager to force everyone to play a certain way. It's neither a cheat nor exploit or unfair in any way if it's a feature, and advertised. Battlefield isn't even a competitive game, why do you even care about other people's progression? Especially if your argument is that you enjoy the grind, then it shouldn't bother you.
You are right. Being against bots for other people is like, in other games, being against medium difficulty modes when you only play hardcore or permadeath. It does not affect the way YOU play nor the way YOU progress. And just think about setting up a really competitive hardcore rulseset which is high demanding skill-wise, you can't event make it run because of capacities issues.
