That may well be the case in some instances, but chemical research tends to have to get done before the patent, mostly.

The replicable details in this example show that they weren't simply making it up.

Still a valid point for devices, and generic chemical patents on groups of compounds, some of which may not have been, and may never be, synthesised. The specific duties of a patent examiner specialising in chemistry-related patents is somewhat outside of my field, however.