Adam Silver works for the owners of each team so he can’t make new policies without at least a majority of the owner’s consent, I mean he is trying to make the NBA regular season better and more valuable to sell to Networks. I know it’s coaches and Presidents who set out their own policies but alot of owners are very hands-on.
It is the same reason there is a salary cap. To save a subset of owners from themselves and not make other owners do the same in reaction.