Why use X-UA-Compatible IE=Edge anymore?

Question

I\'ve taken several online courses lately and I still see some instructors add the following meta tag to the top of their documents by default:

Answer 1

As long as it is set to “Edge” it validates as HTML5, and I'm told it only causes IE to re-render the page if the site was already rendering it in Compatibility mode. Still, putting it in the server config (.htaccess, etc.) is better than putting in the HTML of each page.