Comment by coffeefirst

I would argue the stricter rules did take off, most people always close <p>, it's pretty common to see <img/> over <img>—especially from people who write a lot of React.

But.

The future of HTML will forever contain content that was first handtyped in Notepad++ in 2001 or created in Wordpress in 2008. It's the right move for the browser to stay forgiving, even if you have rules in your personal styleguide.