Wow! That was so well explained that I understood the first third of it.
I visualize it as the same sort of thing that voice to text does when it is only expecting numbers (phone dialing), they rarely get it wrong because they know what to expect. Because of the constraints, it only has to do a small amount of work to verify its analysis. This frees up the channel for outgoing work.
Then you said the word "replay" and I started getting lost. But that's good, a month ago I would not have understood a thing.
Replaying means verifying all existing transactions when a new node downloads the blockchain from scratch.
In the past three-and-a-half years, I learned a lot about crypto by doing exactly what you did here: I kept reading articles I didn't fully understand.