I'm not the original poster, but I also force my browser to render in a particular font (specifically, same font used in the rest of my desktop applications).

In my experience, I'd say about 0.5% of pages are fancy demos of things you can do with web-font support, 1% of pages use custom web-fonts but look just fine without them, and 0.1% of pages are like GitHub where they actually require a custom font. Everything else uses some "web safe" font, and often very little care is given to selecting which one. Forcing everything into the same font is an excellent solution for the 98.4% of sites that don't use custom fonts, and an decent solution for 99.4% of sites.

It should be noted that most of the "easy reading mode" extensions only work well for article-type pages, not for sites like Hacker News or Reddit.

> forcing everything into the same font seems a bit excessive;

Worst case seems to be that you go to a site and it's not quite as pretty as it might be, but still perfectly readable. I'd take that in exchange for not having to press a button to make a site more readable.

Can you give examples of the sites you're thinking of?

edit - that should be "worst case provided sites aren't using fonts to display nonstandard icons".

All browsers I've seen that allow you to override settings allow you to do it by family (sans, serif, fixed, etc)