I've been in web hosting since '95. Back in the day I was the Tech Lead for IRS.gov (1998-2000). We had BIG IRON (hand me down HP K Class servers) from another failed IRS project. They were big, literally 1 server per rack, and we had to build to support all traffic on Tax Day (April 15th). No cloud, few MSPs, Akamai was in it's infancy. We had Cisco Local Director load balancers and grew to geographic load balancers (Alteons). I personally had to forecast peak traffic and we built for peak load.
Tax Day was always like that scene in Das Boot (1981) where the the U boat is sinking and the hull is being crushed by the pressure. That stress peaked on the 15th. For reference:
Months of work and worry all come down to a single day. No way to add more capacity, no way to slow the onslaught of late taxpayers. To make it even more fun, numerous firms (Red Alert, Intuit, etc.) were tracking and reporting our response times throughout the day. There was no escape. Just prayer that you made it through without crashing and burning.
Now we scale automatically, by default. Yes, it's better, but not nearly as exciting.