It's true that you can somewhat increase your overall return by deferring capital gains taxes because you get to hold on to the assets you would have paid in taxes longer and those assets can earn a return for you (this is why certain types of tax advantaged retirement accounts are nice). But I think you are significantly overstating the potential gains when you say that you can save 10% a year.

For example let's say you have $1000. Tax rates are 15% and annual investment returns are 8%.

Under strategy A you sell and pay taxes at the end of every year. Under strategy B you only sell at the end of 30 years and pay taxes all at once.

Under strategy A you will end up with $6,738.55. Under strategy B you will end up with $8,069.6 which is about 20% more.

20% more is a lot so that's a strategy worth thinking about! But it's not reducing your tax bill anywhere close to 0.

In fact you actually pay more in total taxes under strategy B in nominal terms (and about the same in real terms assuming 2% inflation) because you have more overall gains.

Overall, I agree that deferring tax payments can be a very useful thing to do. I just dispute your statement that "Push it off long enough (without interest or fees) and you pay arbitrarily close to 0% tax rate." That's simply not true.

What tax rate does it take before: (1000) * (1 + 0.08 * (1-x)) ^ 30 = $8,069.6.

Plug some numbers in and it's ~9.9% effective tax rate not 15%. Extend that from 30 to 300 years and that % keeps dropping.

The numbers are even lower if that initial 1000$ was profit not principle.