I disagree. The article author is likely referring to the period when IE version 6 was the major browser on the market (from 2001 to 2009), a time many of us fondly remember as the web development ice age. It absolutely did lack features present in other browsers, such as SVG support, transparent PNG support, the full scope of CSS 2.1, countless standard JavaScript APIs (remember jQuery), etc. Rendering bugs added insult to injury, but the lack of features was real. Microsoft didn't release IE7 until 2006.
