I don't doubt that if one is going to file a VFR flight plan then one should put one's intended route on it correctly, just in case one has an accident.
What this has to do with preserving the workload at the Heathrow fax filing facility, I still haven't worked out
what you know about NATS and the Heathrow FBU could be written on the back of a stamp with a whitewash brush
I agree. A pilot does not need to know the internals of the system.