STV does use multi-seat constituencies (as do most PR systems but that's by the by).and the only way to then reflect the other votes is in multi-member constituencies. you end up with a party block, which is slightly different from but very closely resembles a party list. may as well just go all in.
Party block is basically what you have in council elections if you cast all your votes for candidates from the same party, which causes even more distortion than FPTP. Crucially, it has nothing to do with STV and as far as I can tell is just another straw man thrown up to justify an indefensible system.