Put yet another way, if you ask me "why isn't foo done?" I'll most probably just answer "because I haven't had time to do it, and nobody else took the time to do it. If you ask me "could foo be done then?", I'll answer "sure, patch welcome". If you ask me "I've had a look, we could just apply this patch, move that, do this, and then we get foo done", then the time for me to actually do it becomes almost zero, and thus I'll happily do it. Yes, it means spending time on how to do it, but if nobody else spends it, I'll have to do it, but god knows when I'll find time to do it among all other urging matters.
Samuel