I use that mode because it does not cut anything out of the article and will include pertinent images included in said article but none of the side advertising or even most ads inserted within the column. There has never been anything else on those pages of any worth that I can tell.
If I wanted to look at the side advertising I don't do the reader.
It you had used a ad blocker for example UblockOrigin, you would see real time ads and everything else trying to load. Ub puts up an icon upper right on the browser task bar and you can watch the numbers rack up.
I was watching some AOL vid and article and within 20 seconds there were 220 things being blocked and counting. These things are ads, all the side ads and any random vids.
I've been on uboob just to watch like a 30 second hockey vid and almost 300 vids normally loading in the background were stopped. I also use a thing called unhook which is a uboob filter and works quite well. I use it to try and stop that fucking video side load on most these sites.
Want some temp internet fun? Do a search on your own computer for folders called 'temp' 'temp internet folder' and others. If you find one, go to your top window menu and click 'view', select large icons and put a check mark in 'hidden items' as well and open the folder. I guarantee you will find images you never downloaded or even saw while surfing. And you will have 100'smegs to gigs of shit in those folders.
Here's one to check if you have windows.
Start > Windows System > This PC > Local Disk (C:) > Users > (your name) >
AppData > Local > Temporary Internet Files.
And in the same AppData folder ... > check Local Low, Roaming for more temp internet folders.
If you're the administrator of your own comp, you shouldn't have any trouble opening these folders.