alt Hacker NewsThis sounds like a nonsense comparison, no? Surely we can agree that different typefaces have different legibility? And yes, some are serif and some are sans-serif. Also context matters.
Grouping "serif" and grouping "sans-serif" and comparing the groups' legibility is just a stupid undertaking to begin with.
It's certainly not nonsense; it's directly addressing myths created by inadequate or misinterpreted studies.