It might just mean the follower signed-up, verified themselves, followed the person that signed them up, took their introduction payout and quit the platform after a few posts.

Then they aren't using their higher weighted voting power, so no problem at all. Their voting power is returned to the community which is active.

On the other hand, there are people that sign-up, engage in the site, follow the person that got them to sign up, engage with and follow other like minded people and add value to the platform.

And presumably these are the ones that continue voting as well.