[safety1st]

It's not that there was a push for the browsers to be lenient - I worked on a browser team. We didn't want the leniency. We hated it. We wanted a strict parser. I was a pro XHTML guy - I was eventually argued into submission with a very simple and great point: "If we can't parse the whole Web and our competitors can, people will stop using us."

Like, there was no choice in the matter - it was give the market what it wants, or die. Any "push" came from observing user needs and how many people we'd break and drive away with strictness.

Competition mandated compatibility. Engineers might want purity, but users don't want a browser that barfs on malformed pages. Remember that one of HTML's basic principles was to be more lax about syntax than XML. The Web had committed to being syntax-relaxed from day 1. Not caring about markup correctness helped the Web win.

It took me a while to see why it had to be this way, but I was eventually convinced, XHTML would have departed from both what the Web was designed to be and what users wanted it to be.