>If you don't know the names of your representatives you can't vote for them. Seems pretty straight forward to me.

The names are printed on the ballot, along with party affiliation. No memorization needed. In a primary there may be a bit of research needed, but even then you get a sample ballot beforehand so you can research the alternatives, but when the final election happens you generally only have two choices in the US per position and you simply vote for your party of choice.