>First, capital gains and dividends have basically the same tax treatment (not identical, but close enough for anyone holding for longer than a year).

No, that's not correct. If you are being paid a dividend, whether it be qualified or not, that money is double taxed. Once at the corporate earnings rate and then again to you personally at capital gains rate.

As a shareholder, whether that tax all comes out of your pocket or not, doesn't matter. Your increase in value is effectively taxed at 60-70%.

But that is not the case if the company you invest in, rather than retaining earnings to pay dividends, reinvests into growth or other capital expenditures or keeps large sums of untaxed money in overseas accounts. Thus continually pushing the stock upwards. And allowing investors to make their own choices about cashing out. Be it by selling shares of getting loans using the stock as collateral.

Why in the world do you think Apple has $250B in cash, a full quarter of their total market cap, mostly stashed away in tax free zones?

It is for the simple reason that people can invest and get that money reinvested for them all without ever having to sell or take a distribution and then get taxed before using it or reinvesting it yourself.