Power is power, I agree there, but there are different ways of achieving that power.
The other thing is, that chart is imo very old and outdated, its applicable to clearomiser's, I'll grant you, but they deal with tiny wires, limited wicking and fluid delivery, rubber insulators, poor airflow.
When you see people talking about say a mech with a rebuildable atomiser and high output cell, starting at 35 - 40 watts and tapering downwards from the first test fire, their using much thicker wire, better wicking, much greater airflow, which in turn needs more wattage to maintain coil temp.
You use your vamo at 7 - 8 watts, I'm hazarfing a guess at some kind of clearomiser, I didn't get on with clearomiser's, I could also never smoke boxed cigs, both were too tight, I always smoked roll ups, in vaping I absolutely needed that same free airflow you get from drilled or more expensive styled atomisers with open airflow.
Build them with .2 kanthal and run it at 7 watts ony vamo, I'm lucky to get a whisp of vapour, my vamo currently has a fogger v2 with a 1.4ohm tiger coil (.5 ribbon and .25 wire twisted together ) I run it at 15watts and would turn it up if I could, no its not burnt, with cotton in the correct amount that it wicks without flooding, the flavour is amazing, my kayfun is running dual 1ohm ribbon micro coils, (I was hoping to get it high enough to run on the vamo too) again, its just above 15watts on a mech, no burning, the airflow is so much greater that the expected high temp/poor wicking/burnt juice doesn't happen, I have alchemists cupboard banana and cream in it, the vapour is like warm cream on the inhale, not much vapour on the exhale but a lovely after taste.
Yes power is power, its just not everything in the equation, you also have to consider what your applying that power too.
As a side note I use Panasonic based 3400mah cells in my vamo, I do use other mods alongside it, I like tanks and I like different flavours so as I saud elsewhere, I like to havr a few mods on hand, I get about four days out of one cell in my usage.