It gives an unfair advantage because not everyone can do it. Me included =(
LEGIT reasons for why it’s banned:
-Not everyone can do it
-It is stealthier than running, yet makes you faster than running, making it again unfair
-In maps like Dust2 where you can get some speed, makes it hard to shoot the hoppers
-I can’t do it
-It could potentially give you Arthritis in Real Life.