basically what zith said.. It can be done but 10+ years ago it was alot easier to commit that time while playing games plus it was new and exciting.. hell look at diablo 3 and all the time those guys have been in dev.. getting PAID and putting in hours with a HUGE team and it's still not out..
Ya not a fair comparison for a retail game from such a mammoth company but still.
If we had that kind of manpower working on a wf game.. I mean look what happened in q2wf and q3wfa with just the amount of maps from freelancers, let alone all the other q2/q3 mods.