> approval voting doesn't allow you to express your preferences very well
yes it does, in the aggregate. because the people who approve only X or only Y will statistically have a pretty similar X-vs-Y preference as all other voters (who approved both or neither).
https://medium.com/election-science/expressiveness-6ef8c034b...
and because approval voting uses the preferences it does have more accurately than IRV, it ends up being much more accurate, as measured by voter satisfaction efficiency simulations.