I would say that a Benefit for new players is to get more familiar with the Moors by exposure to more experienced creeps. Also, creeps in general (At least when I was a full time player) play much better in groups, as opposed to wandering around by themselves. Being in a tribe helps that.
Unless you're anti-social, have feuds with most other players, or just have a particular play style that causes you to walk around alone, there's no reason for any creep not to be in a tribe.
[charsig=http://lotrosigs.level3.turbine.com/1321301000009f9aa/signature.png]Arachnorexia[/charsig]