No one in work is on a level playing field - we all have different jobs, at different levels and earn different amounts of money.
Why does it take a day out of work and money spent to house individuals in one location, to see others from a different perspective. That's part of human nature....no?
Exact - it creates hierarchies and seniority and that is what causes a number of team related problems.
An off site with a common shared activity is proven as an excellent way of removing the hierarchy and letting us see the human aspects of our colleagues ... just because we are not focusing on that detail they forgot to pass on to us, or the invoice they are hassling us about, and can focus on them instead.
It is a major error to think that team building is only for teams with problems - even the best teams need to consolidate the tea relationships on a regular basis.