Perfectionism doesn't necessarily result in death marches and a crap product. Look no further to Valve to see what perfectionism can mean in the games industry (can I have my HL2:E3 now... please?), and of course let's not forget the obligatory reference to the master of perfectionism, Apple.
The difference between these two companies and the making of DNF? As Steve job said, "Real artists ship".
The downfall was perfectionism.