You can up vote posts you think are useful or interesting. This adds to you reputation.

As you gain reputation you increase rank amd increase the functionality of your profile.

The problem with the old dt forum was we kept getting spammed by people selling my items they didn't have.

In order to sell om thos forum you must have X amount of reputational points. In other words you can only sell once you have contributed. This differs from posts. Anyone csn post. But contribution is different.

Other stuff like post limit will be lifted and your title will change with your rep.