> w3schools says

Never follow [W3 Fools](http://www.w3fools.com/)  :)
Seriously, lots of the things criticized in the link above have been improved or fixed, but I often find better advice in [MDN docs](https://developer.mozilla.org/en-US/docs/Web/HTML), or also [WebPlatform Docs](http://docs.webplatform.org/wiki/Main_Page) (when I'm not actually reading the spec directly).

> My guess is that when someone strikes out text, it is mainly due to an edit in an article

Yeah, maybe. TBH we'd have to look at real usage stats. Feel free to change it if you prefer.