“So if — in your imagination — users that have trouble reading text change the default font size in their browser (despite it not doing anything on most sites), I highly recommend using rems.”
Yes this is why using rems is a good idea! By representing you’re content in the way the user is asking for you are providing a better experience. Why aren’t other big websites doing it? Good question… maybe working with rems on a giant website or application can’t be justified due to increased overhead with impacts to design, development, and testing… All the other big names are doing it, no ones going to shame them… yes pixels will get the job done.
When you are letting a custom font size of the browser adjust the sizing of your content, breakpoints in pixels will let you down. It’s basically like zoom without the zoom. Without setting breakpoint in rems when sizing in rems you’re break points are going to get weird when custom fonts are used.
I know a lot of people are going to read this article and be like “YEAH F*** EM REMS!” Yes, using rem’s is more challenging that using fixed units, but hey at least they gave us rems to work with instead of ems. If rems don’t fit for you don’t use them, but please don’t try to discourage others from trying to make the web a better place.