Skill in what? Roleplaying? Character building? Tactical decisions? Problem solving? Being a good storyteller? Being a good peacekeeper and organizer?
D&D is not like playing Risk or some other game. There are so many elements to the game that it's just about impossible for someone go be good at everything. Just like our characters, our players often gravitate toward filling the roles that each of us tends to do best (or think we do best).
The most important thing is having a good time, and that doesn't require expert skill levels. Even the newbies can often bring something fun and interesting or a different perspective to the table.