The article lays it out into two steps, with "Step 1" being to `cordon` and "Step 2" being to `drain`. My understanding was that `cordon` used to be required to (safely) drain a node, hence why so many tutorials still show it, but that on newer versions of K8s, draining a node will automatically cordon it as well.
Of course, if you want to keep the node up and running, but evict the pods, then absolutely that is when `cordon` _should_ be used.