You can mark vehicle yourself from air yes. But that takes time. Time that can be saved by other players marking enemy tank too.
Your argument is basically “git gud scrub” which isn’t valid nor helpful in this situation.
That said, there is a tendency of enemy marker point being useless otherwise. But on the other hand, plane player doesn’t bother markering mere infantry position.
I play on console and a couple months ago the mark literally just stopped working for me and another dude I play with, but was fine for another friend. Don’t know why or how to fix so I can actually mark
Yesterday I fought in Berlin all day and there were few marks, had one match in Stalingrad and enemies and tanks were constantly marked by players, despite that half of the team were probably bots.
Players that do understand the mechanic and need support does use the system.
I just mark wherever I see enemies.