To a modest extent, yes, which is why modern SAM's like Patriot and similar are so feared. They are very good. But even mobile SAMs could be considered essentially fixed when compared to the flexibility of a fighter. The fighter allows one to project power along any axis, very quickly, to extreme ranges, and also respond to enemy fighters. There are also horizon issues - by flying at higher altitudes, airborne radar gets a huge range boost compared to SAMs.
One cannot send a Patriot 1,000 nm into enemy territory to attrit enemy air.