In the early 1990s and early 2000s web development was a nightmare. Having to test not just in different browsers, but different versions of different browsers,

In the early 1990s and early 2000s web development was a nightmare. Having to test not just in different browsers, but different versions of different browsers, because they had substantially different behaviors. There was no "Inspect element", JavaScript debuggers were entirely absent or incredibly crude. Getting a decent looking web page to render and function correctly across all the different browsers you supported was a real achievement. You spent most of your time fighting browsers, not making actual progress.