It's about levels of abstraction. Transistors aka super tiny solid state switches are one thing, and then from them you can build a few (maybe even just a single NAND one) gates - and now you're only thinking in terms of gates. This model does not simulate transistors, it's basic elements are gates and their combinations (techincally the atoms - the builtin, hardcoded, axioms, things that just *are* and you cannot break them down further are AND and NOT and my suggestion was to make NAND a single fundamental unit).
I feel like my explanation is pretty bad as this is something that seems intuitively obvious to me (separating this ideal abstract model with gates that we're simulating here from reality where everything is quantum physics anyway lol), apologies for that