I don’t think conventional finance theory was ever to conflate stock price and valuation the way you just did there. Nor did it only include dividends in NPV calculations.
And I’d argue that valuation based on NPV of future profits hasn’t fallen apart at all, it’s just become harder to estimate future profits, and the discount rate has changed.
When I was a kid, the valuation of a company was based on the amount of profit that it did taking into account the cost of getting it.
The day that the USA abandoned capitalism for speculative-finance was a bad day for the world economy.