To tell the real from the fake. lol
It must be well hard to make a fake tag.
And if you feel you need to say "Look my timbs are real". Then you are very insecure.
I personally think it's very sad to leave the tags on. Do you also wear clothes with huge labels on them. Just so everyone knows you've spent a lot of money. I spend a lot on clothes. But I buy them because I like them, not so everyone knows I have spent a lot.