Assignments have good and bad side for gameplay, some of the stuff sure tells people "hey you can heal and give ammo to people, or build these covers here"
But then there is also those "get 20 kills while prone, 60m or more" of course that kind of assignments are hard to do and people try to do them, while being useless because game teaches so.
In general I think, honestly now, most people are very bad and simple minded players, I mean most games these days are really simple, dont have to think about anything, no skill level, no skill ceiling, just press button and things happen.
You can see this in almost every match of BF, people just camp, doesnt push, sit in some corner with their MG/LMG fearing that someone might kill them and lose their 1KD.
When game comes that might need you to do something, they ignore most of the things they can do because they are used to simple gaming.
But Dice is to blame too, they should explain game mechanics and things, there barely is anything explained anywhere outside few tutorial vids to show gamemode and assigments.
I just today learned that as medic you can press the spotting button on some downed teammate to tell them you are coming to save them, while you do this you get that speed boost that the basic medic skill gives, that is not explained anywhere you could do that.