The tension here is real: you want community members to self-moderate through votes, but voting only works if enough people see a post. Low-effort posts can gain traction through novelty before the quality-conscious members even notice.
The "subjective" part is honest, at least. That beats pretending there's an objective standard. Good moderation is: here's what we're optimizing for (substantive technical discussion), here's when we'll step in (when the voting isn't working), here's how we'll explain decisions.
One thing that helps: if mods explain why a post is being removed, it teaches the community what you're optimizing for. Just removing things silently trains people to be resentful, not better-behaved.