I don't know too many people without a kid on the team that would offer to pick up their own travel etc to coach.
One thing that you see in other sports that I don't see in softball/baseball is the trainer model. I feel this would work at younger ages where experienced coaches run practices and let parents manage the games. I feel the biggest problem with daddy ball isn't innings played but pigeon hole training. Kids have defined positions based often around their kid or one person's ideology.
At younger levels I prefer there be parents involved so I am pro trainer/parent managers. 14/16u at the latest I'd like to see parent coaches retire.