Clever software marketers have realized that a $999/mo SaaS product fits under that limit just as well as a $999 boxed product.
Yes, almost every large company has different purchase requisition approval processes based on the amount and often the type of expense, but they vary widely between companies and roles. There’s nothing magical about $1000 vs $500, $250, $0, or $2500. I’m not even sure $1000 is the mode; at least from my small sample, $0 and something larger ($2500 or $5000) are more common.
Also, in nearly all cases I’ve seen, large companies determine the approval process for anything with a monthly fee differently (generally using the total 1-year expense). If it ever existed, the “clever exception” is long gone now that companies buy a lot of SaaS.
Finally, usually larger enterprises are using SAP, Oacle ERP, Coupa, or a similar “Procure to pay” (yes, that’s what the category calls itself) product, and they have really complex approval rules by ledger category, not just amount.
(My own theory is that patio11’s otherwise-good blog post simplified things so far that many readers thought the specific thresholds it gave were a lot more common than they ever were.)