You might be able to fly the plane in a reasonable facsimile of normal flight if you can fly the simulator and you have natural ability. The problem is that if and when the plane is acted upon by natural forces of wind gusts updrafts and a myriad of other factors you might not have time to think about the proper control inputs to save your plane. Instructors usually have a lot of experience flying and react instantly to the problem and save a plane where to newbie has a small brain lockup for a few seconds becuase he is unfamiliar with the controls and orientation of the plane. One of the big problems that a newbie might find himself in is banking an aircraft and instead of righting the aircraft by reversing the ailerons he inadvertently rolls the plane inverted. the new flyer might not realize all the options to recover the plane. If you have altitude you give up elevator and do a half loop. Giving negative elevator to try to right a trainer from inverted is almost always a bad choice. giving negative while trying to roll a plane is ok if you are to low for a half loop but trainers are very slow rollers. An Experienced pilot would attempt a negative snap roll if he had minimal time but a newbie would not even have time enough to think of the manuveer. Instructers keep you in the air and give you stick time and experience and help your plane live through bad choices