Parsons pointed out that there simply has to be someone in charge, or society would descend into chaos and nothing would get done. If no one has the power to make decisions, then no decisions get made. When society is effectively organized, choosing one person or group of people to give power to actually gives everybody more power over their collective situation.
To understand how this works, think about a coxswain on a rowing team. The “cox” doesn’t row at all; they just sit at the end of the boat and coordinate the rowing by calling out to the rest of the team. In a sense, the cox has “power” over the rest of the team in that they can tell the rowers what to do and when to do it — but everyone on the team understands that without a cox, the team’s rowing would be uncoordinated and they would be wasting a lot of effort. By giving power to the cox, all the team members gain power over their opponents; if each team member kept for themselves the “power” over when and how to row, the whole team would lose.