Most large scale web applications spend their time reading and writing data, both to/from clients and to/from other remote services such as databases. You don't need thousands of hosts. Stackoverflow famously ran 9 server instances in 2016 with 7 dedicated to the primary sites.
Unlike postgres, Oracle and Sql server can support thousands of connections but they see performance degradation at a certain point. So I have never seen them crash from too many connections(Although they definitely get slower.).
Unlike postgres, Oracle and Sql server can support thousands of connections but they see performance degradation at a certain point. So I have never seen them crash from too many connections(Although they definitely get slower.).