Sure it is: https://support.mozilla.org/en-US/kb/change-fonts-and-colors...
> So if user set say 14px as their preferred font size, it would be 19.6 px instead. That's just asshole design.
I don't see that as any different from saying "use 19.6px text unless the user specifically overrides it." Maybe the designer just likes big text! If a user doesn't, they can easily make it smaller.