It's true that ads use bandwidth and battery but ad-blockers and web standards implementations built into browsers are not "free" either. It takes CPU to find

It's true that ads use bandwidth and battery but ad-blockers and web standards implementations built into browsers are not "free" either. It takes CPU to find and strip out ads, and bandwidth to contact filtering servers or whatever else guides the behavior of blockers (and generally the more blocking you opt in to, the more of this there is). I have seen an astounding drop in Chrome performance when using HTML5 YouTube videos on my laptop, where attempts to scroll and click take seconds to even respond and I haven't yet figured out why. I would still expect the cost to be less overall without Flash but it would be interesting to measure everything that is really going on and figure out if ads are really the worst offenders.