I recently discovered thanks to this blog[1] that you can print with netcat. This was impressive to me, but even still, it doesn't completely solve the problem. Instead it moves it from handling the data for printing on the client's side to handling it on the printer's side.
These issues will arise when you try to print a pdf(pdf is a particularly complex file format. More explanation and discussion can be found here[2]). As such, because there's a long precedent in supporting it, it's best to conver a PDF to Postscript(otherwise the printer will spend a long time processing the file, or just fail because like I said, it's a complex file format).
The command for printing if people are interested is `nc printerIP 9100 < document.ps`. Suffice to say, this was a very interesting read. Thanks Retrohacker!
P.S. In the example provided, where pdf is the proposed alternative, I disagree. I think Gemini is the current viable alternative. I don't think it's in a position where network effects multiply, so the only adopters are technology enthusiasts(and even then it's relatively close in structure to HTML in the mid 90s).
[1] Retrohacker, bye cups, printing with netcat