If a company buys back shares from an existing investor (EI), EI now has cash and is likely to either spend that money (if they're a retiree selling shares for income) or reinvest that cash into some other investment. It's very unlikely that they're going to keep that new money in cash or a savings account.
Or suppose they buy a painting from another billionaire for $20 million - did that really create any jobs or middle-class wealth?
You can argue against the tax implications of buybacks vs dividends but either corporations give profits back to investors or they will just have to continue to grow bigger and bigger, which I think the same people hate even more than buybacks.
But we live under capitalism so giving money to people is out of the question. Money is for billionaires and shareholders.