Stiftung (Foundation) generally work well if you have a bunch of money and you basically have a fixed "algorithm" that you want to execute around the money like: "Invest it all into an index fund, and in any year in which the fund returns a profit, pay out the profits to the family members of person X in the same ratios that would apply if those people came into X's inheritance". You then appoint a bunch of lawyers to serve as the board of the foundation. Because the "algorithm" is so precisely defined, the set of circumstances where the lawyers do their job wrong will be well-defined, and will constitute a breach in their fiduciary duty. There's basically no room for making entrepreneurial decisions along the way. It's a bit like taking a pile of money, putting it on a ship, putting the ship on autopilot, and giving up any and all direct control of the ship. Depending on what precisely that "algorithm" actually is, this might get you tax advantages. Or it might create non-financial positive outcomes you might be trying to achieve like making sure that your progeny will continue to enjoy the wealth you created for many generations to come while limiting the probability that any one generation can screw it all up for the later generations.
Social entrepreneurship is different from that: A social entrepreneur wants the goodwill and favourable tax treatment that comes from giving up their claim to ownership of the money generated by the business (this is what the gGmbH status does; it's a bit like 501(c)3 in the U.S.) -- But they want to retain control over the business. They want to make entrepreneurial decisions as they go, changing strategies along the way in whatever way they please, without restricting themselves too much to the execution of any predefined programme.