Webmasters should master the web
I am fed up with non-standard web sites, but even more fed up with webmasters that claim they just have to tweak the simplest html to render properly in different browser versions. Wrong. Since the late 90's, all browsers have rendered standard html in virtually the same way. It's just incompentent webmasters who do not know or do not care about this.
I found a good overview of how different browsers react to different doctypes. The summary for dummies (and webmasters) is: Use a standard doctype, and you are fine.