Barnstorming on an Invisible Segway

I'm a bit worried that people who call themselves science fiction fans have read little enough of NPR's list that they feel unqualified to vote. Despite what quibbles I may have with the list or whatever, it does pretty much cover the territory. If they are fans of the genre, what are they reading? Not trying to be critical. Is this a "I need to have read at least 90% of the list" perfectionism kind of objection, or is it a "I've only read one book on the list and have never heard of tho others" kind of objection?