Yes I agree that the multiple to earnings will likely always be...

Yes I agree that the multiple to earnings will likely always be constrained by the factors you mention. And yes, your point about capital fleeing indiscriminately is a very important one (something that has been occuring in a number of 'legacy' sectors, as 'tech' has soaked up all liquidity). On the other hand, I see tomorrow's earnings (barring recessions/pestilence/lockdowns/war/asteroids/etc) as being potentially higher as the business continues to leverage its increasing scale & capital deployment opportunities. This moment in the sun will end - and when it does, the market will likely be right in applying a 'constrained' multiple. But for the moment (in my best estimation), that multiple is neglecting the fact that the retained 'e' (or EBIT or EBITDA) in the metric is creating substantially more than one dollar of value for each dollar deployed.