"Pretty cool though, but they don't stress all the keys."
They don't have to. Why would the "d" key be any more prone to failure from repetitive use than the "y" key? Testing multiple keys at the same time speeds up the process, it shouldn't alter the failure rate.
The keyboards will fail if left in a hot dry environment for two years. Whether the keys are pressed or not. They will also fail if you drop liquid on them. They want to impress us with the keystrokes and not look at the real reasons the keyboards go bad.