Running a simulation in a browser is not going to be a complete representation of reality. To think that is possible is really weird. So really, what is happening, we are arguing over the 'Title'?
Because I think we would really be arguing about, what level of reality can be calculated in a browser. Sure, a simulation can be done in a browser. But that could be anything from a thermostat with a single simple equation, to modeling all of the air flow thermo-fluid dynamics in a house down to millimeters volumes. There are limits. And I guess if using WASM browsers have gotten a lot more capable. It would come down to what fidelity we are saying is 'reality'.