The fast switching ability isn't a bug by itself, but it makes the insecure authentication much worse. Shitty IOT auth does not mix with power electronics.
Whether Tesla is worse than other providers in this space is another question, and may well have a depressing answer.
The fast switching is still a failure of defence in depth.
It could be internally rate limited to some value (which I don't know), and also with some random backoff value so Powerwalls could not be synchronised.
Whether Tesla is worse than other providers in this space is another question, and may well have a depressing answer.