added a comment - - edited
Well, technically (as you noted) it will work to set a string value via Store and then increment it, but I think that's unintentional behavior and works only because (as Attila pointed out in the linked issue) of the way counters are treated on the server. The correct use of the API should be to initialize a counter with Increment or Decrement by setting the default value.
Either way I think there's an intentional step imposed on the developer. I think it's better to discourage setting a value as a string to initialize a counter, since that's not very intuitive.