If I had a server with 100 cores to serve 100 connections, but each query took only 5ms, SQLite might be totally viable. There's no blanket solution.

Edit: More importantly, SQLite async limitations come into play when I have only 12 cores but 100 incoming connections, and on top of querying data from SQLite, I do have other CPU bound work to do with the results. If I had 100 cores, 100 connections to the database would be no problem at all since each core could hold a connection and block without problem.