Sidewinder...I take your point and I defer to you as usual.
I have heard this before.
Cylinder locks (the ones with the brass cylinder in the mechanism)
usually fail prematurely because the tumblers corrode in the brass
body and then sieze up, freezing the mechanism.
I have lubricated mortise locks for years; and had 20 years service
out of them. A lot depends upon the material. Graphite has been
suggested but I NEVER use one famous brand because the primary
ingredient is wax with a diluent to lower the viscosity. Once that
diluent evaporates...all you have is wax and this gums up the lock.
The petrochems industry has a problem with huge amounts of long chain
paraffinic waxes and the industry launders it by this and other means.
A high quality distillate oil, the likes of which one might use on Hornby
trainsets, is more suitable.
Your observation regarding lubrication is also pertinent to the clock makers
and repairers. Even here, in this august and sagacious body of finely
tuned minds, arguments rage about whether or not to lubricate escapements.
John Harrison solved this at one swoop when he was a cabinet maker at
Nostel Priory in Yorkshire. He made a clock with an escapement of wood.
Incidentally, was at my Mum's yesterday. She has now been advised that
the lock mechanism is a security risk. Work that one out.