In the US, progressing up the the hunter and equitation divisions before moving over to the jumper divisions is still the most common route.
It is possible to show in unrated or schooling jumpers without the hunter/equitation background, but those riders tend to "top out" pretty quick in the 3' - 3'6" divisions. If you don't have the foundation developing pace, balance and direction and keeping a steady rhythm and consistent arc around the entire course, being able to "turn and burn" only gets you so far.
If you look at US show jumpers, including Nations Cup and Olympic riders, the majority came up through the hunter/hunter seat eq ranks. I can't think of a single one who *didn't* come up throught those ranks.
Now, in other countries, the hunter and equitation "feeder system" doesn't exist; and they produce competent jumper riders without it, but their rider's educations and show experiences are also very different from ours. (No 18" Table C classes
So I recommend you get a good, solid foundation in hunters before going over to the dark side.