You most certainly don't get it, because any time people mention that's why they use jQuery they are blasted with YDNJ website links and told to learn vanilla JS as if they don't already know it. I don't use jQuery much any more, I enjoy using Vue or vanilla JS, but I do use it for smaller projects that are brochure sites because it's just faster (and WP includes jQuery by default still). There's always been a reason to use jQuery and it didn't just suddenly change, there's just way more options now.

and it isn't just down to syntactic sugar. The guy gave an example in the article. Bootstrap rewrote for v4 and excluded jQuery, but in the process dropped IE support and wrote their own helper functions any way.

Almost all the people that instantly say "OMG JQUERY ISN'T NEEDED ANY MORE LOL LEARN PROPER JS" don't even know vanilla JS themselves and started learning by jumping straight to react.