Most of the racers' intuition was built by running hundreds of test laps, figuring out the car, the track, the tires.
Modern F1 can't do that.
Maybe to cut costs ditch those simulator amusement rides and let the teams actually drive the cars at test tracks.
The testing was ditched primarily because it's much cheaper to simulate than to test (4-8 times cheaper, depending on whether we're talking about Ferrari at its home track, teams testing after a race weekend*, or a UK-based team having to fly somewhere with warm weather, and also depending on whether the test timing requires an augmented team)
* - Due to the wear rules, you'd realistically need each team to send an extra car over just for testing (at least for its regulated internals). Thus teams testing after a race is more expensive than Ferrari testing at home (where they just send their test car(s) and crew over from the factory next door) but cheaper than UK teams testing in, say, Spain (because they must fly over entire cars plus necessary personnel).