I just started @JoshWComeau’s course on CSS and loving the platform so far. However, I'm very put back by this statement about CSS units for box model properties: "pixels [are] more intuitive than rem, and there isn't a clear accessibility win".
I'm no accessibility expert, but clearly there are a lot of benefits to sizing everything in relative units. Here’s Josh blog for example, with pixel based widths, with a 300% text only zoom.