Dihedral is a friend. It is what allows free flight models to stay airborn in stable flight for extended flight times without any control input of any kind during the flight. It helps trainer aircraft train newbies. Back in the days when I first started in RC (1962, years after I had been flying free flight and control line) most of us flew with rudder only, or sometimes with rudder and throttle. No elevator, no ailerons. Without dihedral, or without adequate dihdral, smooth turns were essentially impossible. In fact, without dihedral, the plane would eventually fall out of the air. With dihedral, rudder only or rudder throttle equipped planes had a number of possible pattern manuvers, including consecutive loops and rolls. When aileron control became practical, the need for dihedral became reduced.

Even now, if one were to loose aileron control in a plane with some dihedral, the plane possibly could possibly still be steered for possibly a safe landing with rudder. Without dihedral, loss of aileron could end up in a rekitting. Had both happened to me, BTW.