The retro pixel art aesthetic is just that - an aesthetic. It's intentional and doesn't accurately reflect the technology it imitates, because it's about a vibe. The people creating Geocities webpages weren't professional developers or artists trying to adhere to a particular aesthetic, they were regular (mostly non-technical) people doing what they thought looked cool at the time, or just copying other sites and using the graphic elements or templates provided by Geocities.

Pixel graphics were still pretty much current at that time. Not everyone threw away the SNES/genesis when the next gen systems came out, most people probably still had one.

And to do the pixel graphic style you need a pixel font which was impossible because you can only reference fonts people have on their computer, Fixedsys font was the best you could reference and some did do that.

Sure but we're talking about personal/hobby pages made by people who are overwhelmingly not artists and designers.

Pixel graphics were still pretty much current at that time. Not everyone threw away the SNES/genesis when the next gen systems came out, most people probably still had one.

Geocities was not for professionals. It was for amateurs.