I am all in favor of "functional fitness." Beginning around 35, the human body begins to deteriorate. Unless you are a competitive athlete, fitness is for daily life. One of my daughters was talking about fitness this weekend and opined that a Div 1 singles tennis match was a good work-out. I asked "Are you sure?" After a moment's thought she revised her opinion: No, I guess the physical training is the prep/work-out, and the competition is just the reward.
Playing sports is mostly calisthenics at best. Many sports require strength and athleticism, but actually playing the game is not the same as a work-out. Think baseball, or the several seconds of effort in a football game. Training is for life and games, but they are not training.
I thought this approach was interesting and it sounds even more fun than Crossfit: Get Fit Like a Wild Man: A Primer on MovNat
More on MoveNat
As I said, it sounds like great fun and challenge and bonding but it amounts to heavy calisthenics, which is just one of the three components, in my view, of a balanced fitness program.