That's what's possible today. It wasn't back then (see: https://en.wikipedia.org/wiki/C10k_problem https://en.wikipedia.org/wiki/C10k_problem) The other reason

That's what's possible today. It wasn't back then (see: https://en.wikipedia.org/wiki/C10k_problem https://en.wikipedia.org/wiki/C10k_problem) The other reason is, not every web server, web application, database, etc is optimized for large number of connections. Sometimes they take up too much CPU and memory. Sometimes each page request triggers a connection to a database, so the database connection limit is hit. Sometimes the queries are inefficient and slow the database to a crawl. Sometimes the sheer number of packets causes so many interrupts that it sucks CPU away from the application/database. And sometimes the network connection of the webserver was just slow. Most people hit by the /. effect were not just a simple web server serving static content. Often it was a php website with a mysql database, on a server less powerful than a 2015 smartphone.