Large organizations don't buy the way individuals do. Their purchasing runs through procurement platforms, and to sell into them your store has to speak the same language: cXML, OCI, hosted catalogs, and SSO for buyers.
That's what PunchOut does. A buyer starts in their procurement system, "punches out" to your catalog to build a cart, then returns the order back into their approval workflow. Done right, it turns a complex enterprise sale into a normal ecommerce flow.
We built TakoApp to bring PunchOut to WooCommerce, because the enterprise buyers were there and the tooling wasn't. If you're trying to sell into procurement, it's a shortcut worth knowing about.