While those connectors are marketed as power jacks, there is no reason why they can't be used for other purposes. I would strong argue against off-label use, because you just know a user will plug a wall wart into that jack which was repurposed as an output!
That said: I have a few of these DC power jacks in my personal library and they are built with the pin types as passive, and I add the Power Flag to the nets as needed.
Why? Consider using the jack as a low-voltage AC input. In this case, the center pin doesn't feed a regulator input, but instead goes to a rectifier whose output feeds the regulator. The connector doesn't need to be a Power Output, and you still have to put a Power Flag on the rectifier output to satisfy ERC.
Remember: WINU (Windows Is Not Unix). What likely happened is when Kicad was installed, the program and its libraries were put in the Program Files directory, which in modern Windows installations is not writable by users. Most Windows users put the libraries in some location they can control.