Those features are the madness of standards enforced under penalty of law. CSS is a recommendation, and the only penalty is a competitive disadvantage. Back when the Internet was a graphically simpler place with a browser monopoly, there was little disadvantage to implement CSS however they damn felt. If Ford sold 90% of cars and a consortium recommended they add 12 new safety features, imagine how they'd respond.

In case of CSS, the important browser was IE.

This reminds me of DOCTYPE switching. From http://hsivonen.iki.fi/almost-precedent/: "Back when the Quirks Mode and the Almost Standards Mode were introduced ... committees created specs and that were enshrined as W3C Recommendations before there was solid implementation experience. Then the Web Standards Project lobbied browser-makers to implement the W3C specs as they were. The mindset was that the specs given from above couldn’t and shouldn’t change. People thought that vigorous upgrade evangelism would work and make Web authors change their existing sites."

Note that the Web Standards Project was also the one petitioning Netscape to cancel Mariner, which ended up contributing to the problem. Why did non-IE browsers have to implement document.all?