Well lo and behold I was right about historical weather.
Changing the sim times stops you being able to use live weather.
This needs to be made optional asap.
Screws up flight planning as winds are incorrect so fuel calculations all wrong, screws up vatsim in many ways, aircraft will be doing different ground speeds with same IAS given by ATC will cause huge spacing issues at busy airports. Runways will be all wrong as winds might have changed and different runways in use. Aircraft will all be at different altitudes as the pressure might be different.
I predicted this would be an issue, and look it is.
Hugely disappointing.