[jsjohnst]

There's a couple reasons for PoE not supporting over 36W but USB-C supporting PD at up to 100W.

1) PoE only uses two pairs of wires for transmitting current, USB-C PD uses four pairs.

2) Ethernet cables are rated for much longer lengths, show me a 100m USB cable.

3) Ethernet is typically run in walls and more often than not is grouped into bundles, so heat dissipation is an issue.

4) PoE delivers power at ~50v, USB-C PD does 20v.

Also, piggybacking on the other commenter's reply, PoE voltage is carried on the same wires that are transmitting data (for 1000Base-T anyway)