It doesn’t matter if you call it hybridization, grafting, or cross breeding. They are all natural trait selection processes.
I'm not inclined to agree with you here about grafting. The only grafting for trait selection processes I have ever been aware of need assistance. Hybridization and cross breeding most usually occur because of natural pollination, although both are more commonly done now under controlled circumstances by humans.
Grafting may occur in nature but if so it is extremely rare, it is a common practice in horticulture. Grafting is NOT a trait selection process in the same way as hybridization or cross breeding. Grafting can be used to create a PLANT combining the traits of two or more different PLANTS but it does not produce fruit or seed with a combination of traits. A grafted plant will never produce offspring that combine traits of two different plants as cross breeding may, it could be compared in animal terms to attaching a head from a German Shepherd to the body of a Russian Wolfhound. If you want another like that you have to do it all over again. If you want to produce offspring with a combination of traits you must BREED the Shepherd and the Wolfhound and then you can continue the process to produce a new breed of dog. It is not even the same as producing a TRUE HYBRID such as a mule for instance, a mule does combine traits of horse and donkey but is infertile so that combination is not passed on.