I clean, sanitize, rack, and cleanup in about an hour with kegging. That's fully disassembling the keg. I bet some people can do 1/2 hour in their routine.
I freaking love kegging.
Don't get me wrong tho, it does come with it's own set of challenges. Tracking down leaks, finding your carbonation method (I do not care for fast carbing), cleaning the lines, etc.
I don't know, it's just worth it to me. I don't like bottling. Bottling day is OK, it's just all the bottles everywhere, everyday in between. Drink a beer, rinse the bottle, dry the bottle, store the bottle...it's too much on a day to day basis. Bottles bottles everywhere.
But to answer your question, yes you can just condition in a keg just like bottling (although use less priming sugar). I'm just starting to do that now, and I think I prefer it.