If your listening to those with experience, I have over 40 years of it. Ammonia even in small quantities burns a fishes gill membranes. Yes, many fish can tolerate small amounts for awhile. Corals are killed almost immediately by any concentration at all.
Fish less cycling is less cruel as there is no "test" fish. All organic laden sand and rock comes to you with a lot of dead material in it that breaks down into ammonia fast. This occurs during shipment and storage. In many cases you don't even need to add a dead shrimp or ammonia to get the process started.
If you graph the nitrogen cycle, you will see it is rhythmic. It is always pulsing up and down. A new tank has these peaks crossing into the kill zone. A cycled tank is when those pulses flatten out and the nitrogen cycle isn't swinging back and forth dramatically. IMO it is safer for this to sort it's self out without livestock present.
