This all rings true to me. I would take it a step further and say that during normal times throughout the history of corporate America, and especially in boom times, management will let fiefdoms grow fairly unchecked. Then an external trigger causes them to re-evaluate and that's when they're like "holy shit we don't need nearly this many people."

For those of us who have been around the block (i.e., are old), the only times I've personally seen companies aggressively cut personnel is during economic shocks (dotcom bubble and housing crisis as two examples) and only then were the companies running lean (I wouldn't even say they were running bare bones; it's the only time I've seen headcount actually optimized for the work being produced).

I think the Twitter purge was actually an example of a major trigger. Not on par with the previous two I mentioned (obviously), but it was so high profile that anyone in tech took note of it, which is why I made the original comment. I've never seen so much discussion around a layoff for a company that was not imminently imploding (some may say Twitter was about to implode, but if you said that at the time I think you were wrong regardless of the state of its financials).