Not considering speed/efficiency, I don't recall scripting being the worst in IE. (Although, alerting users to scripting errors with alert modals was pretty unf

Not considering speed/efficiency, I don't recall scripting being the worst in IE. (Although, alerting users to scripting errors with alert modals was pretty unforgivable.) My biggest gripe was the poor CSS support. And though it gave us the border-box model, as you mentioned, it was legacy IE's normal box model, which didn't comply to standards. Which is the whole point. Because IE was the most popular browser by a landslide for many years, developers would code specifically to deal with IE's non-standard interpretations of web standards. It was a sad time. Either your site looked like crap in IE or in everything else. Depending on the year or era, that meant developers would make it look right in IE and shrug their shoulders for everyone else since they were just playing the odds. But no matter your outlook on which users you defer to, that's not a choice any developer should have to make.