Not very convincing, IMO, to just say "if the POG had folllowed the rate of inflation". No particular reason why it should...
well, not very convincing, perhaps, but to be fair, its not phrased as an argument for current price, just a statement of fact ...
as an argument, though, its probably more convincing than "this tech company is growing at a 50% yoy clip right now and, if it can sustain that growth rate for 5 years, it deserved a p/e over 100."