That may be a tad exaggerated but it is at least 75% in my estimation. It is only a guesstimate but made on the basis of information. The following are my top 3 clues for spotting bots.
1. Anything that is a corporation, or event, or travel guide, or anything that is obviously not meant to be a human being is a bot. In my case that is only about 5–10% of my followers.
2. Followers that have accounts that look like this are almost all bots

A fairly high number of people following but zero or just a few followers themselves. They almost always “just getting started on medium”, have zero posts to their name, and typically do not have a profile or profile pic though that has evolved from the beginning and more do have pics then don’t these days. This represents the vast majority of my followers 50–60%.
3. Accounts with obviously fake or made up names. These are actually the only bots I like and I have had a ton of fun writing stories about some of my favorites, Ucaca Wa and Uranus Yoda being my top two all time favs. These make up the remaining 5% or so. In addition to the great names their accounts almost always have the same characteristics as 2.