Can you point out an example of a constructive use of such extension? Or are we fully into "We built the torment nexus from the classic novel Don't Create The Torment Nexus" territory?
Here you can just Upload a CSV of Contact numbers, and put message and Hit Send.
It need not be just your contacts, it can be anyone.
It had a large demand, where people were not willing to use APIs be it Official Whatsapp APIs or UnOfficial ones like Maytapi
Here you can just paste CSV and Hit send
Mainly used in Cold Whatsapp Outreach
Again, I'm probably just too stupid and I'm missing the legitimate reasons for an extension like this other than "Spam thousands of whatsapp users from your throwaway accounts".
I'm sure you can illustrate them better than I can.