The players who bought this game do. You are writing off 8 customers with that attitude.
Some players do care about their 4v4 rank, but there are so few teams playing 4v4 AT regularly that the ladders are not a very meaningful indication of anything. I don't like how people translate this by saying "nobody cares" about 4v4 rank at all. Especially since it seems to imply that nobody cares about 4v4 balance, which is absurd.
That being said, it's much easier to obtain a high 4v4 rank than a high 1v1 rank, or 2v2 AT rank. As a result, those ranks are much more respected.
Even then, I will never really understand how the ranking system works. Why is cruzz higher than me in USF 2v2 random with a record of 18-5 and a streak of -1? Beats me.