In the 80's and 90's there were thousands of tech small businesses.
Later, as the cloud phase heated up, the efficiency of scale became more important.
Ranking algorithms in particular are necessary to sift through the firehose of content.
Historically the best way to do ranking algorithms was sifting social processes; collecting billions of human interactions in the system and using them to drive an emergent sort.
This only works with massive amounts of data, which means only the biggest platforms can do it.
But LLMs allow human-level judgment available to anyone, and might make ranking with much less input plausible.