They're not always batched. They're only batched within the context of an Event listener. A fairly odd distinction made necessary because React rendering was made synchronous initially but I guess it works for most apps.
The fact that it's currently within the context of an event listener is probably the wrong way to think about it. The only sane and safe way to work with setState is to think of it as scheduling a change to be made at some point in the future, and that batching will occur if possible.
It's clear from the post that the author didn't learn how setState works, he's not aware of either batching or the callback form, which neatly address most issues related to setState.
I didn't pay much attention to the second half of the article, because I avoid heavy use of Redux anyway. Ultimately the author shouldn't have even been looking into Redux before understanding how React works, so presumably he's been misinformed somewhere along the way.
It's clear from the post that the author didn't learn how setState works, he's not aware of either batching or the callback form, which neatly address most issues related to setState.
I didn't pay much attention to the second half of the article, because I avoid heavy use of Redux anyway. Ultimately the author shouldn't have even been looking into Redux before understanding how React works, so presumably he's been misinformed somewhere along the way.