My thinking of 'deny all' is something like facebook where everyone seems to like to embed little bits into their pages. But I used to also use facebook. So if I made it work for one I would accidently make it work when I did not want it to on external sites.
I have been using it like this for so long I hardly even notice it anymore though. But that is just me. If I give this sort of solution to anyone I usually just give them an adblocker. That gets most of the silly things.
HN is one of my main news sources and due to its link submission nature I frequently visit sites I have never visited before. It seems like 90 percent of submissions need at least one round of whitelisting just to see the text content. And frequently a second or third round to get embedded code snippets or other relevant content to load.
It's tiring and I noticed that I frequently just give up and copy paste the url into an alternative browser without blockers.