With hybrids, you get the vision of RGP lenses with the comfort of soft lenses. That’s the theory anyway. Why bother? Why not stick with one or the other?
The problem with soft lenses is that, although comfortable, they are very thin and flexible and drape over your cornea. This is fine if it is a normal, healthy cornea with a regular shape. But the problem occurs when you have an irregularly shaped cornea (such as in keratoconus). Soft lenses just don’t provide a regular surface in the way hard lenses do. BUT, hard lenses (RGPs) are not tolerated well by everyone.
Keratoconus is often associated with allergy and itchy eyes, and the hard edge of the lens can irritate some people to the extent that comfortable wear is not possible. This used to mean giving up on contact lenses and making do with the poorer vision provided by glasses. Then along came the hybrid contact lens.