[plorkyeran]

Reader mode probably has a pretty low impact on ads. The full page is usually going to load before you activate reader mode, so the only ads it's actually hiding from you are ones below the fold, which are much lower value to begin with.

[extra88]

Not if you use Safari's feature to always load pages on a domain in Reader mode or add a Firefox extension that does the same.

Gizmodo articles should load in Reader mode but don't, I assume they're doing that intentionally.

[lolinder]

Yes, but at some point advertisers have to realize that people who use reader mode don't actually see the ads. The ads might load, but the user is just staring at the reader mode button waiting for it to turn on.