I disagree entirely. Charging rate is charging rate independent of battery capacity.
I don't understand all your posts, and didn't bother reading them. I could be wrong, but it seems straightforward to me.
If I hook up a Volt, it charges at the same rate initially as a depleted Tesla with double or triple the battery capacity.
A Tesla contains thousands of individual batteries. The individual batteries are rated to X amperes of maximum charging current. A battery pack is limited to X*N (N being the number of cells to create the pack) of maximum charging current.
Splitting that battery "pack" in half means that you have two batteries each of N/2 size. So each pack can take X*N/2 maximum charging current, which means your total charging current for two packs is 2*X*N/2, or X*N. You've changed nothing by doubling the number of charging ports or chargers.
If splitting the packs in half and doubling the number of charging ports would increase recharge rate, why would Elon Musk not have done it at this point?
BTW if you hook up a Volt to a 250 kW Tesla v3 Supercharger, it won't fill at 250 kW, because the battery can't accept that much current.
If I have one 10 L bucket and one hose to fill it with water, it will fill at half the rate of two 5 L buckets and two hoses.
I get 10 L twice as fast with two hoses.
The problem is that you're ONLY looking at this from the flow rate of the source. You're not looking at it from the rate at which the battery can accept charge, which is the limiting factor.
If the hose output is the same, then you'll fill one 10L bucket twice as fast with two hoses as you will with one. Along the same lines, if you have two 5L buckets, you'll fill them with 2 hoses AT THE SAME RATE as you will fill one 10L bucket with two hoses. It doesn't matter whether it's one 10L bucket or two 5L buckets if the hose flow rate is the key.
What I'm saying is that with batteries, it is NOT the hose flow rate that is the limiting factor--it is the battery cell maximum charging current.