Maybe it only works in the US equity markets, but that's not "only works in the US" -- the S&P 500's companies are: not all based in the US, and in total derive only 75% of their revenues from outside the US.
For reference, the US share of world GDP is about 25%.
It would not surprise me at all if the most scalable, profitable, and growth-oriented companies ended up on the S&P 500 regardless of where in the world they started or where their revenues originate.
I'm not saying anything about interest rates -- your point there might be spot on -- but US stock markets have huge global exposure, and your implied assertion that there's some kind of "global" benchmark equity growth rate doesn't seem that sound.
The point he's making, which is well known, is that while in the US stocks and index funds derived from them dominated all other forms (bonds, real estate, etc), it's almost never the case in any other developed country. For most of the recent past (recent meaning the last century), putting money in index funds would have been suboptimal in almost every country out there.
The fact that the companies get a lot of their revenue from other countries is moot. In those countries, investing in index funds is not the highest performing long term investment.
My post was in response to the prior poster's claim that US exceptionalism here doesn't have a clear rationale, and that one might expect some sort of "reversion to the mean" where "mean" there is the performance of broad equity markets in other countries.
In my post, I'm saying that one shouldn't expect that broad markets indices to grow comparably in other countries, and the fact that they don't says little about how well they do/should/will perform in the US.
For reference, the US share of world GDP is about 25%.
It would not surprise me at all if the most scalable, profitable, and growth-oriented companies ended up on the S&P 500 regardless of where in the world they started or where their revenues originate.
I'm not saying anything about interest rates -- your point there might be spot on -- but US stock markets have huge global exposure, and your implied assertion that there's some kind of "global" benchmark equity growth rate doesn't seem that sound.