GPT-3.5 (unfinetuned) has been matched by many OW (open weights) models now, and with fine tuning to a specific task (coding, customer care, health advice etc) can exceed it.

It's still useful as a well known model to compare with, since it's the model the most people have experience with.

I think they mean the assumed parameter size of GPT-4 is so large you couldn't run it on commodity hardware even if you could get hold of the model.

The rumored GPT4 model size is 1.8 trillion parameters