Because not everyone who reads what you write knows what they are doing. Anyone can do a top end. It's simple. Not everyone is an expert like you and will/can take the time to figure out why they're doing it in the first place. Build your motors your way, but what you have to remember is that not everyone that reads how you do it knows what you know. Maybe the OP is a rookie and needs all the help he can get to keep his motor running. Dry assembly, in my opinion, is not going to help him.
Why would you be starting a new motor with an air leak, or a setup that could in any way be lean enough to make a fresh motor ping?