That’s not modern in my opinion, because we’ve been doing it for at least a couple of years.
Agreed. “Modern” web development IMO would talk about Gulp, bower, React, etc. Also the submitted link looks too much like linkspam to me.
I would argue that in a couple years, we will still consider HTML5 and CSS3 to be modern, and people will be saying “Oh yeah, React, I remember that.”
HTML is now essentially a living standard, which means that whatever the living standard says will be modern. As for CSS, a similar thing has happened and it has been split into modules such as “css-selectors” and “css-flexbox” allowing them to “level up” individually. HTML5 and CSS3 may still refer to the then-current version at any point in the near future but the content will have changed significantly.
To be honest I’m not sure what you’re arguing for since we aren’t talking about what will be modern but rather what is modern.