I know the 'general' answers: "it allows the yeast to 'clean up' compounds", "it allows the beer to 'condition'", "it allows the flavors to come together", none of which I am satisfied with.
My question is: given proper-to-over pitch rates, cold-pitching (to minimize acetaldehyde/diacetyl production and precursors), and careful monitoring of fermentation temperature, is there any practical reason that homebrewers cannot turn beers around quickly, like in a commercial brewery? Is it diastatic pressure?
For instance, I made a California Common last fall, and was just below a lager pitch rate for a 5G batch. Pitched at 60*, fermented there for 4 days, fermented 4 more days raising up slowly (2-3*/day) to 70*, cold-crashed for 12 hours, gelatin, racked, quick-carbed and served. And it was great.
I'm not saying I didn't get lucky on the above-batch, but for any beer below say 6% alcohol, I would love some information on what is happening to the beer after FG is reached.