Breaking up companies can be a mechanism to enforce openness. For instance, the proposal to separate Microsoft's application business from their OS business (in

Breaking up companies can be a mechanism to enforce openness. For instance, the proposal to separate Microsoft's application business from their OS business (in the late 90s) was in reaction to them giving their own apps special treatment in their OS, so their apps ran better than third party apps. By separating the two business units into separate companies, they would lose the incentive to do stuff like that. Separating Android and Chrome from Google Search would limit the obvious temptation for abusing their browser business to help their advertising business. Google has (so far) shown pretty good restraint in their tactics compared to what would be technically possible, but the incentives are massive and might be hard to resist when times get tough. Enforcing openness in the face of massive incentives to the contrary requires prompt and wise government oversight, which is hard to achieve. The range of subtle tricks that platform companies can pull to slightly break their competitors software is beyond the ability of regulators to control.