But it's not always about cadence. For example there's the hub gear type advantage of changing to a very much lower gear in advance with a single action when approaching a stop point, for me important with so much cycling done in urban areas with lots of stops.Fair enough, I understand the workings but personally I've only ever wanted to move one or two gears with my thumb shifters to keep a suitable cadence. If I was to move 10 or 11 gears, which I have, I would be totally confused as to where I was on the cassette. Added to that, on some of the off road up-hills that I do, I would be twisting the grip by mistake while I'm trying to bend the handlebars back.
I sometimes even like to jump up several gears when entering a downhill so I can pedal with gravity and increasing speed to immediately gain lots of extra speed. That's useful when there's an uphill following that I want to hit at maximum momentum and kinetic energy.
I don't do tough off-road uphills, but I have plenty of 20% and even 25% uphills on roads round here and have never accidentally twisted the grip back.
All of which emphasizes that it's horses for courses, your needs are obviously very different from mine, which are utility cycling biased.