If I have X dollars and get taxed such that I have X * T after the taxing, say T = (1 - .20), then I invest and that money grows by a factor, say G = (1 + .50), over the years, then in the mean time inflation hits and reduces my money by a factor, say I = (1 - .10), so that what I end up with in the end is F = X * G * T * I. If instead I invested and grew and inflated and then got taxed, X * G * I * T, it would be exactly the same. Multiplication is commutative.
What you are doing by delaying taxes is hoping you have a lower rate later. Say you make less in retirement or die untaxed and your kids get a step up in basis. But without a change in rate (which might go up even), there’s no difference.
If you take a loan against your larger capital pool, inflation helps you (to the extent it wasn't incorporated in higher lending costs).
But yeah that's a second order effect. There aren't really any scenarios where you have a fixed nominal tax that can be deferred without locking up the money, so I think you're mostly right that it comes back to lower tax rate and step-up.
Good point about inflation. Deferring can make sense. I was thinking what we earn today is more enjoyable to spend today than when we have bad knees and whatnot.
What you are doing by delaying taxes is hoping you have a lower rate later. Say you make less in retirement or die untaxed and your kids get a step up in basis. But without a change in rate (which might go up even), there’s no difference.