True for base PoE (802.3af, 15.4W), but if you have PoE+ or greater (802.3at, 30W and up) you can start to power more common PCs - I’m running a couple repurposed Chromeboxes from PoE++ adapters.
Nice to have an official HAT - I've been using PoE splitters without issue for the last year or so now (on Model 2 B+ and Model 3 series) as an alternative.
