I think the 0% floor is more of a matter of things starting to become wonky when you hit negative rates. People will just start hoarding cash instead of receive

I think the 0% floor is more of a matter of things starting to become wonky when you hit negative rates. People will just start hoarding cash instead of receive -1% / year of their money. This will cause a bank run of mass withdrawals, banks currently have 0% reserve requirements, so could be insolvent from even minor bank runs...