My contention is that pronouncing doom for hiring in the software sector based on a graph that does not include any previous boom/bust cycles is, at best, misleading.

I actually didn't see that these data are HN-specific, but that only serves to reinforce my point in two ways: 1) HN is only a small sample of the overall industry, and 2) since HN hiring presumably skews disproportionately toward the startup/VC funded ecosystem, it's likely to be even harder hit by interest rate hikes and economic downturns.