To me, the only question is "Is it actionable?"
If it isn't actionable then it's nothing more than an interesting bit of information.
And Jim says that it's not actionable, but just a bit of information.

I think it's actionable information, just not actionable in a market timing kind of way.

For example, when the broad US market is cheap (according to CAPE or any other "good enough" metric), just buy the market. There is no need to be discerning or nimble or smart, just enjoy the ride and you will do well. This is also not bad advice when the valuation level is in the middle range.

But when the broad US market is expensive--i.e., you aren't getting many future dollars of earnings for your money--your choices are more limited. You can live with low returns, or be judicious in your stock selection,or go farther afield, or invest privately, or try your hand at market timing if you're feelin' lucky, or try short term trading by quant or momentum or other methods. Or sit on cash till it's time to pounce.

So knowing the valuation level is definitely actionable in that sense: those are quite different actions. Just not actionable in the sense of telling you whether the market is going to go up or down next.

Jim