GNU/GPL folks are zealots about user freedoms, not license. Linux leadership (accepting GPL) are less zealotic about user freedoms, but sometimes are zealots about keeping control (rejecting to play nice with the OpenZFS project). BSD people are zealots about getting rid of GPL code so that their product can be used by some stranger in a proprietary way. There is money both in working on GPL software and more liberal licenced software (GPL variants), but it seems everything is set up so that the two camps must not directly cooperate.