New plants can be propagated by seed, cutting, layering, aerial layering, grafting by one of many ways, and even micro-propagation such as tissue culture - or, as occasionally happens, by sporting.
So far, hibiscus have not responded well to tissue culture.
Sadly, they don't grow true to seed.
However, they are so easy to grow, most varieties anyway, by cutting. A few difficult to grow by cutting are usually grafted.
Seed growing is left to hybridizers who gamble that they will get better than the one-in-a-hundred keepers usually experienced.
Then again, you may find a sport of an existing variety and propagate that.