That's right. HTML has finally caught up with what Flash has been capable of for many years. It's not the technology, it's how people use it. The Flash Player I could easily turn off, HTML5 I can't. The ad industry can't wait to start pushing HTML5 ads.

Do people really not remember the time when adverts were animated GIFs?

Adverts were blocked before Flash, non-Flash ads are being blocked right now by various means, and they will continue to be blocked in the glorious HTML5-ad supported future.