Video doorbell dual battery powered

I’m confused on why Eufy say this in their description and FAQ. The battery powered dual has screw terminal on the rear for constant power and for the existing chime connection. So why do they say it cannot work? This makes no sense.

Can the battery doorbell work as a wired doorbell when it’s hardwired?

No, the battery doorbell cannot work as a wired doorbell. If you have existing doorbell wires and prefer to hardwire the doorbell, you are welcome to purchase the wired version. We will begin selling it in late March