They’ve used that exact same symbol since they first added an Ethernet port to their computers in the early 1990’s. It was one of the first mass-market computers with integrated Ethernet. It literally defined the standard when there was no standards body for such a thing.
It's a joke, note the conflation of port (physical connector) and port (one of 65536 virtual TCP/UDP pathways for applications). Also, HTTP(S) (port 80 or 443 by default) is literally "Hypertext Transfer Protocol" so it's fair to say it was designed to carry HTML.