You were not serving that traffic, you were just serving your core functionality - no tracking, no analytics, no ads, no a/b, no dark mode, no social login, no responsiveness. Are most of those shitty? Sure, just let me know when you figure out how to pry a penny from your users for all your hard work.
Oh no, not the dark mode! The sacrifices we have to make for performance I guess...
Easy. We built something that was worth money without all that.
Not a one trick marketoid pony.
We were serving around that traffic off a single dual pentium 3 in 2002 quite happily off IIS/SQL Server/ASP. The amount of information presented has not grown either.
That little box had some top tier brand main corporate web sites on it too and was pumping out 30-40 requests a second peak. There was no CDN.