I think you are mostly right about the reputation, age, and your sp. Though I'm sure you have gained a few legit followers since you put in the work.

I seem to have to seek out legit followers myself sometimes. So much gets posted. It's hard for everything to get lost in the noise.

I myself have never signed up for the auto upvote thing. It's always been manually.. it's easy enough to spend my so manually curating for me lol..

Anyways congrats on 9k followers. Keep up the good work or else, you are appreciated!