Hypothetically, if you smeared dog shit all over your lawn and watered it, Wouldnt that help your grass grow?

ewwwww

My understanding is that there are so many nasty chemicals in it your lawn would die.

Dog is an omnivore and who knows what all they eat. Their shit isn't supposed to be manure and it's definitely not good for a lawn.

Not good. Probably mostly gonna grow fungi.