That’s how it is in this part of Maryland. Even the local elections are partisan, so the real election for county executive, sheriff, etc. occurs during the Democratic primary election. If you’re unaffiliated (like I was) then your primary ballot will only have a couple of referenda; the general election might as well have a single candidate for a particular office given the high unlikelihood that a non-Democrat might win (if and when there’s an opposing candidate). I finally registered as a Democrat this year just so I could vote for Bernie in the primary.
ETA:
Well, there was the mechanism of using the vote to (if nothing else) ensure who would (or would not) be nominated to the Supreme Court. But here we are.