well, like many people mentioned before, the production is completely up to the producer to mix, organize, write (for original things, re-write for dubs), and sometimes even compose music... and then to put it all together to make it sound good (and it usually doesn't just take like 1 or 2 hours- more like days, weeks, sometimes months).
also i'd much rather a producer be "selfish" enough to self-cast a major role, even if it's 23094823098423098 lines, than to bail out because they weren't interested in doing the project anymore or they don't have enough care to try to finish it.
plus.. another thing a lot of people have mentioned before. how is it selfish for a producer to self-cast when there would be no production in the first place without the producer?
ok, done with my two cents