Except that we know that there have been some systematic shifts which are by themselves going to produce higher valuations now than in the past. One is simply not comparing apples to apples. One of the most obvious of these is shifts in GAAP which result in lower earnings with no actual change in the company’s financials.
This is not clear to me from the macroeconomic data, as the corporate profits share of GDP is much higher than the historic norm.
https://fred.stlouisfed.org/graph/?g=1Pik
On top of which I think there have also been some shifts in what one might call corporate strategy. Notable in this I think is an increasingly common orientation for companies to pour cash flow into future growth, not caring about earnings,
This is not visible in the macroeconomic data on business investment, which is low by historic measures.