Google is the initial assignee and a patent provides exclusionary rights to the inventor of a technology. Great if someone else thought of it earlier but no one published anything using it or thought to get a patent, because otherwise this very important patent would have been void and it wasn’t.

Robin Li's rankdex patent predates pagerank, see https://patents.google.com/patent/US5920859A/en?oq=US5920859... as well as the pagerank patent, which cites it.

Patent US9165040B1 does not cite US5920859A, I’m not sure what you mean.