I put one of those graphics on my very first angelfire site, because all I had was IE and I hadn't checked how it would work in anything else. When people started paying me for web development, though, I started installing browsers, operating systems, and even acquiring whole new devices (wap phones) to see how my client's sites were rendering in the real world. I spent whole nights agonizing about tiny tweaks and compatibility hacks to make sure everything looked good, this was the majority of the job in the early aughts. Now, in 2018, if you stick to a somewhat conservative set of html and css you can build nice looking sites that render great in any moderately modern browser across thousands of devices. It's insane to me that web developers now would rather descend back into compatibility hell by making their sites rely on a stack of unwieldy and opaque javascript.