Why might feelings of friendship between team members remain strong over time\

Because a bond is not very easily forgotten if you work well with the person then you will work or get along together well later on it is like yin and yang you co exist with out disturbance.

or

Responses will vary. A sample response follows: When playing together on a team, all members of a team are working together toward a common goal. There will be many successes and failures while trying to reach that common goal. These shared experiences make the feelings of friendship long-lasting.

it doesn't. it was imagined up in the middle ages.