While I think 10px is a bit small, it is used in things like Google Calendar for the time/date labels. Resetting to 1rem = 10px is more about accommodating our brain’s love for units of 10 and divisibility by 2, not so much that we want to use a 10px font. Switching to em and rem give a lot more flexibility and design unity than using px, so not a bad way to go. One change at the base style can easily effect project-wide changes in font-size, and container size. Just my two cents.