The 0.001 SBD (or STEEM) is the minimal amount required for a transaction, aka dust transaction. They didn't send you that to be generous. Also, it's a way to send someone a memo on Steemit. So, with 1 SBD they can memo spam 1000 users, if 10% of *uninformed users respond to their scam with 1 SBD, that gives them 100 SBD! Quite a ROI.

So, all the followers of those scammers would see 100 resteems in their feed, on top of their own followings. The likelihood of anyone voting for those resteems becomes narrow. So there is no guarantee those resteems will work.

This is why those scammers have 10-80k followings to target, they need volume spam to hook a few minnows 🐟, which they successfully do, if you look at their wallet history.