the relevance is that these earnings expectations are lower than when the dotcom bubble happened.
The fact that a single company can have a market cap today that is greater than the losses from the dotcom bust is irrelevant. We have more wealth today than back in 2000, and these market caps reflect that.
[citation needed]
https://www.macrotrends.net/2577/sp-500-pe-ratio-price-to-ea...
The dotcom bubble peaked at around 46, while we are currently at 30. Will it grow? Who knows. But the bubble certainly isn't as big as claimed by the grandparent comment.
Markets collapse, investments slow/stop, orders dry up, suddenly stocks must be valued on future hypothetical orders post-recession (same company, eventually the economy will turn and someone will buy), current PE values spike as current earnings become decoupled from stock price