I can only suppose that he maybe doesn't have the ad-blocking features in his browser that I (and lots of others) have.
To be honest, I've given up on extensions. Most of the ones that I've used have simply been horrible. IF they even work, they grind the browser to a halt very quickly.
I used to use a few, but simply got sick of the sluggishness. I have far fewer problems with just the simple, stock browser. Some things I'll install, but ONLY if they're 1,000% necessary and I can't live without them, e.g. Firebug.
I recently TRIED to read a CNET news article... Nearly impossible. The page was so heavy with crap in it that I could barely scroll. No problems elsewhere. (I just installed another 8 GB of RAM in this box as well.) Bad page.
I just don't have the patience to deal with <insert more profanity here /> insanity on the web.
I just want the pages to render quickly so that I can quickly get through what I want/need on them, then GTFO.
Now, I have used some extensions that actually were pretty decent, but when push came to shove, they still slowed things down too much.
I think Microsoft really had it right with their basic architecture for running code in a web page. BHOs simply perform beautifully. Compiled plugins just work. I'm not saying "lets' run lots of ActiveX" or anything like that. I just mean that they had things working better.
Then again, I could just be far less patient than most people...