Add to that a not-invented-here / not-invented-by-me problem. A platform with some warts probably could have been fixed by those who understood it. But those people were gone. So the team genuinely needed larger headcount than before the layoffs, in order to rewrite the thing.
If I had to root-cuase it, it's that senior leaders get no points for delivering outsized results with a small contingent of engineers; their prestige and leveling is all about the headcount growth occurring beneath them. So there's no pushback on headcount growth, until there is.
At the very least it can help drum up interest from investors based on "look at the new X we shipped, or look at how strong our team is"
A hiring binge could be a 'hail-mary' attempt to try and save a sinking product because everyone's busy putting out fires.
Or it could be a genuine sign of growth where product development and refinement cannot keep up with the demand for it.
Of course, there's the issue that when a company has lost the trust of internet cynics, there's not much that company could say to convince them of a commitment. maybe a public, long term contract with some organization of consequence... but you can always get out of those by paying fines or malicious compliance.