If you’re going fast enough for a ramp to send you into space, you’re already going sufficiently fast to have a set of wings to carry you the majority of the altitude you need to achieve. And at that point, you’re trying to make a SSTO space plane. But those aren’t currently viable with existing technology due to inefficiencies in current rocket designs.

Earth is big, with a very deep gravity well. It’s not well suited for fully self powered space planes.