This is actually not true because it ignores the fact that a company's shares could be trading cheap or dear. One dollar in the form of a dividend payment is always worth one dollar (ignoring taxes), whereas if the company can buy in a share with intrinsic value of X for the cost of 0.8*X, then it is "creating value" for the remaining shares. Conversely, if the shares are expensive relative to intrinsic value, then a buyback destroys value for the remaining shares.