It's possible to combine event-driven simulation (for digital) and nonlinear differential equation based simulation (for analog) within the same simulator. The simulation engine can be smart enough to mix the two efficiently. As a toy model, consider this 4-bit counter plus DAC (click "Simulate" at the bottom):

https://www.circuitlab.com/editor/53xa3r/

The simulation loop is both event driven (when CLK1 flips state every 0.5 seconds), propagating those changes through combinatorial gates, and analog, simulating the op-amp to create a simple digital-to-analog converter (DAC). Bridging the analog and digital sides within the simulator is tricky, but not impossible.

You are correct that if there were not both event-driven and analog simulation intermixed, and we simply simulated all the digital gates with their analog implementations in MOSFETs, that simulation would be at least an order of magnitude slower -- probably far worse!

(Disclosure: I built CircuitLab's simulation engine.)

Your analysis is correct with respect to circuitverse. This is just to test the logic correctness of your design after abstracting away the analog and real world nature of electricity.