I don't think you should vote like this to prioritize features. It seem complicated, bureaucratic and and smells a bit like "design by committee".

Decisions like this should come from a single person with a clear vision, or be based on real world data (e.g. A/B tests). Don't get me wrong, I do believe that developers should be part of the discussion that leads to the decision. But the decision itself should come from a single person. Not from the result of a calculation.

The spreadsheet might be OK as a tool for the discussion. But I don't think it is a great discussion tool, because it requires to use a computer during the discussion phase. And what's even worse is that it does not add any insights over just a whiteboard with the votes.

So sorry, but I don't think this solves the prioritization problem.