Reposted:
I still remember working on a Nokia project from a good ten years ago, where “for convenience of internationalisation” all action buttons were replaced with icons only. What a fight it was to convince the stakeholders it was a bad idea (we were just an agency, and when this battle was eventually won, it apparently was mostly based on numbers, not common sense).
Designers assuming that their icons – no matter how used they themselves are to them from being on their devices 24/7 – are uniquely understood really should take this story of Matt Wilcox’ mum to their hearts. She didn’t even realize Gmail was not read only! Putting text under icons, too, is inclusive design.