I don't understand the fixation on this. Share buybacks strengthen the stock price of the company, which the company can leverage in the future to raise more capital if needed (by re-releasing new shares to the market). From that perspective, they are better than dividends.
Besides, right now, Apple isn't strapped for cash as they have around ~50 billion on-hand and could raise more if they wanted to. So Apple can still invest more in fab processes if that's what they want.