Each port can accept or give power (at various voltages) potentially or act as data sink/source (determined on connection), or have alt modes.

Such device would be either quite "fun" to use, unless it had type C ports marked with dedicated functionality, so you'd have to be careful what device you plug to what port.

AFAIK there's no protocol to control other ports via PD from the port you'd connect to the "main" device (like your laptop). So the behavior would be all pretty random, or the ports would have to be fixed in function.

My completely unfounded on anything guess is that it might have to do with breaking the chain of "trust" between the different connectors on negotiating how much power an actual downstream device can handle.