That has been the case since art was first industrialized with the printing press. Most of them don’t survive but a significant fraction, if not the vast majority, of books printed in the first century were trashy novels about King Arthur and other fantasies (we know from publisher records and bibliographies that they were very popular but don’t have detailed sales figures to compare against older content like translated Greek classics). Only a small fraction of content created since then has been preserved because most of it was slop. The good stuff made it into the Western canon over centuries but most of the stuff that survives from that time period were family bibles and archaic translations.
I don’t see why AI will be any different. All that’s changed is ratio of potential creators to the general population. Most of it is going to be slop regardless because of economic incentives.