When I first turn on a conventional canister stove, I'll turn it up to a reasonable level.
Then, after a minute or so, due to evaporative cooling inside the canister, the pressure will drop, and the stove will go down to a low level.
It's gradual, so usually I don't notice it until it's way low, then I'll turn it up back to a reasonable level.
This is especially true when it's cold and/or there is less fuel in the canister.
With the regulator, I don't think this would happen.
So, there is some utility to the regulator. It's kind of annoying when I notice the flame level has gone down and it's taking forever to heat up.
But, it's not annoying enough for me to worry about it much. And the Soto people don't talk about this.