Actually vesting would have reduced the other partners leverage greatly. First, they would not have been an LLC, would have already been a C Corp. The partner was refusing to sign the transfer docs so they could become a C corp to leverage outside investment, and give employees option agreements. If they had been a C corp, my friend would have gained more shares with every investment, and could fully control corporation decisions. Vesting also would have made it more clear to his partner how little equity he yet had, and more amenable to working together.

But outside my example, starting any new idea as a 50-50 partnership without vesting requirements is a terrible idea.