Very cool link, thanks.
And it carries much more weight coming from a Fed economist than coming from "some guy" on Seeking Alpha

For anybody wondering why net profit margins have soared, Figure 1 really sums it up nicely.
Interest + tax was around 55% of EBIT around 1972-1992, and has since then steadily fallen to about 25% of EBIT, a fairly steady decline.

This process has taken so long that a lot of observers seem to think that the rate of real profit growth since then is normal and natural and can be safely extrapolated.
But, assuming this process has a natural end, aggregate profits can't grow any faster than sales.
And if the process reverses at all, aggregate profits will grow more more slowly than sales for a while.

FWIW, real total sales from US non-financial corporations rose 1.72%/year from 2005 to 2022.
FWIW, real total sales from US non-financial corporations rose 2.25%/year from 2015 to 2022.
The baseline years were chosen to be neither peaks nor troughs.
Sales data from here St. Louis Fed (FRED): Nonfinancial Corporate Business; Revenue from Sales of Goods and Services, Excluding Indirect Sales Taxes (FSIs), Transactions (BOGZ1FA106030005A) | FRED

Using those figures as a rough guide, at constant net margins aggregate profits "ought" to rise at around inflation + 2%, give or take a bit.
Absent changes in valuation multiples, the real total return to expect from a broad slate of US companies should be that, plus the dividend yield.
Of course there will be changes in valuation levels, but that's hard to predict. We can probably rule out forever increasing multiples.
The SPY dividend yield is about 1.55% at the moment.

From my database, most of whose fields come from Dow Jones News:
A trend line through real S&P 500 earnings since 2000 has risen at a rate of 2.800%/year since January 2000.
A trend line through real S&P 500 dividends since 2000 has risen at a rate of 3.000%/year since January 2000.
The notion is that one should not take this rate of increase as normal--both should be expected to slow down to the rate of real sales growth.
S&P 500 real sales per index point have risen at a rate of inflation + 1.85%/year 2000-2022 inclusive, using data from multpl.com. (again, slope of a trend line fit, not end-to-end rate)

Jim