There are two main reasons the teeth on the sprockets start to show signs of hooking or pointing.
The first and most commom reason for this is that the chain has elongated in pitch. When the chain and sprockets are new, they both have the exact same pitch. When the chain starts to change in pitch, due to wear on the pins and bushings, the sprocket teeth get deformed becasue the chain no longer rides in the valley of the tooth as it did before. It now rides up higher on the working face of the tooth. The higher it rides, the less tooth meat there is to handle it. So, it deforms accordingly.
Another reason for tooth deformation is that folks tend to not adjust their set-up properly. If you have the chain tensioned too tight, this will place an undue stress on both the chain and the sprocket teeth when you land from a jump. Bad tensioning can also wear out your wheel bearings and shaft seals.
It may be a common practice for some to simply remove a link once they have reached the end of their adjusters, but this is a bad move to make. If your chain has stretched that much, then it is far beyond time to change it out. Taking a link out to get your adjustment back can lead to a snapped chain, broken bike parts, and sore body. No offense, oldschool....but that is a bad recommendation.