Screenshot of my Public Notes profile at kindle.amazon.com

Amazon’s “Public Notes” feature for Kindle has been available for months. So why did my following and follower counts rocket up overnight to five times what they had been?

It’s simple. When kindle.amazon.com was introduced in February, you had to manually add users you wanted to follow. Now, if you’ve linked your Twitter or Facebook accounts to Public Notes, you automatically follow other connected users that you follow on those networks.

The old way was a bit of a crapshoot — it was hard to find and add other people unless they...