[Karellen]

> I would expect two large groups of user behavior:

I think you're missing:

3. People who set the font size once, when they configure their browser, to their preferred font size and expect, for some weird reason, that this will be respected!

> The tool to take control of all of that is reader mode, which is a great option when a website has screwed up its typography.

That would be great, if there wasn't a huge correlation between websites that screw up their typography, and websites that use an ungodly mess of nested `div`s and javascript-based content rendering that breaks reader mode.

[marcosdumay]

On Firefox there's a preferred, minimum and maximum sizes. If you want sites to respect it, you set the minimum, otherwise it's a suggestion.

[dspillett]

That third group is small enough that if it is impractical to properly support all three, they are the ones that will be ignored first.