What point are they making? Surely it can't be that the diagram is abstract... Diagrams are by nature abstract.
IIRC, the key to CyberSource Corp. v. Retail Decisions, Inc. (about credit card risk assessment over the internet) was in the precise wording of the claims - they didn't use the word "internet", even though that was how the invention was described. The thing is, the description in a patent is just "one embodiment" of the invention, and it is up to the claims to be clear about the actual scope of the invention. Claim too much and you're dead.
That's why most inventions have a series of dependent claims of decreasing scope - if the court finds one is too broad, the next one might be OK. A ridiculously broad first claim does no harm - provided you confine it later. From reading several patents, I've formed the impression that the first claim is often used as a sort of framework "here's the basic idea", and its wording is more to do with making it convenient to hang the other claims on than intrinsic merit.