alt Hacker NewsCertainly that's a good reason to force a legible version of settings, and the path to settings...
But if the user sets the system to hot dog stand, the apps should be hot dog stand. If the user wants the system text font to be wingdings, they're in for a nasty time, but that doesn't mean an app should force a different font
The issue with this thinking is that it's easier for people to quit using the product than to figure out how to fix the font. You can't beat the simplicity of doing nothing, so you need to avoid getting into this state in the first place.