Correction. Keynes' theory of demand side economics is challenged, criticized, and proven to work only under a "particular" type of market, similar to our "expert's" FA (Which works with little flaw in a bull market). The demand run post war economic expansion of the US was stalled by something which had little to do with demand. With the crude oil price rise of the 70's due to OPEC's oligarchy was something new to the demand side economists who still continued to effect inflation by creating policies which affect demand, later proven ineffective. With modern schools of economics such as rational expectations thought, neoclassical theories, and monetary economics taking a firm ground, Keynes' concepts provide little value in the current juncture.
Noise trading, noise trading by proxy. Hazardous to wealth undoubtedly.
Considering the few trillion variables which affect prices, what was intrinsic value when the expectations were formed differs from the intrinsic value when the govt announced the supply arrangements. Giving 1 static intrinsic value to a stock merely based on expected earning and expected growth of 1 year doesn't look to be very rational. As famous quote goes, "In the long run, stocks tend to stick onto their intrinsic values" (Hypothesis of fundamental analysts) ..."In the long run, we'll all be dead" (A quote by beloved Maynard Keynes).
Your hypothesis: Stocks tend to stick onto intrinsic values sooner or later. Stocks below their intrinsic values tend to out perform the stocks quoting above the intrinsic value.
For this to hold true, sufficient data to quantify earnings expectations, expected growth, and historical prices of equities should be quantified and tested on the data and the result should agree with your hypothesis.
Till then, it remains a myth, a tale not backable by evidence.