Being wary of a person that has spent 10 years in the same position makes it far more sensible. There are still many types of positions where this is fine, but

Being wary of a person that has spent 10 years in the same position makes it far more sensible. There are still many types of positions where this is fine, but there are also quite a few situations where someone might be taking up a slot that someone else needs in order to move up the ranks.