Look at the pictures of bad examples. If at least half of them mildly infuriate you, he's right. I disagree with icons-in-a-text-file with him because in a pinch (when you care so little about the font that you just use sans-serif), Unicode icons look passable if you overlook the platform inconsistencies. Of course, there is no gear icon but what are you gonna do about it? The ⚙️ emoji is close enough.