I'm not sure that "browsing the internet and being shown advertisements on web pages" should be considered a task whose intensiveness is on-par with 3D renderin

I'm not sure that "browsing the internet and being shown advertisements on web pages" should be considered a task whose intensiveness is on-par with 3D rendering, 1080p decoding, or encoding. Browsing the modern web is an incredibly complex activity. Many of those Flash ads feature high bitrate videos, sound streams, and complex interactive elements. Of course, maybe advertisers shouldn't be building such overbearing creations to try to grab your attention, but don't blame Flash for their excess.