Again you have a good handle on the situation.
I live in a town of 14,000. In our civic elections, I usually know enough about a few of the aspirants for municipal Councillors that I can cast a reasonably wise vote for or against someone.In general, I think we usually get a reasonably good council and mayor, despite getting only a 25% turnout at the polls.
But in a bigger municipality, the knowledge of the aspirants is diluted because the electoral districts are so big. Should we vote for the candidate with the most lawn signs?
Likewise in my provincial or federal ridings, I seldom know the names on the ballot. I have no idea whether these people are alcoholics, embezzlers, or wife-beaters. I usually spoil my ballot in these elections as my protest that the system is not working.
The party affiliation gives a voter something easy to latch on to. The big electoral districts ensure the serious flaws of most candidates remain seriously hidden. The dysfunctional nature of party politics ensures that many good people stay out of party politics — leaving the field more open for those with more ambition than talents and skills.