Honest answer first: most of what gets sold as "community building" on social is actually audience building with better marketing copy. They are not the same thing, and treating them like they are is why so many brands have huge follower counts and completely dead comment sections.
A community has a reason to talk to each other. An audience has a reason to watch you. If your entire strategy is "post value, get followers," you are building the second one and calling it the first.
The tactic that actually worked for us, and it took me longer than it should have to figure out, is what I call "answering in public." Specifically on LinkedIn, where SEOSkit does most of its organic work.
Here is what it looks like. Whenever a client asks us a real, specific question in a Slack or on a call, something like "why did our rankings drop after we changed the URL structure," I rewrite that question and answer as a LinkedIn post the same week. Not a watered-down version. The actual answer, with the actual reasoning, sometimes with the client's situation anonymized.
Two things happen. First, other people in similar situations start commenting with their own versions of the same problem. Second, they start tagging each other. That second part is the tell. When your content makes people think of specific other people in their network, you have stopped being a broadcaster and started being a reference point.
The proof for me came about eight months in. Someone I had never interacted with posted a question about entity salience on LinkedIn, and three different people I did not know tagged SEOSkit in the comments before I even saw the post. That is not audience. That is community doing work on your behalf when you are not in the room.
Engagement metrics lie about this constantly. A post with 500 likes and no comments is quieter than a post with 40 comments and people replying to each other. I stopped optimizing for the first number a long time ago.
The rule I keep coming back to is simple. Stop asking what will get the most reach. Start asking what would make a specific real person send this to a specific other real person. That is where loyalty actually lives.
Everything else is just noise with good lighting.