The short answer appears to be "we are cheap and nobody cares yet."

It's easy to damn the torpedoes and deploy straight into production if there's nobody to care about, or your paying customers (to the extent you have any) don't care either.

Once you start gaining paying customers who really care about your service being reliable, your tune changes pretty quickly. If your customers rely on data fidelity, they're going to get pretty steamed when your deployment irreversibly alters or irrevocably loses it.

Also, "staging never looks like production" looks like a cost that tradeoff that the author made, not a Fundamental Law of DevOps. If you want it to look like production, you can do the work and develop the discipline to make it so. The cloud makes this easier than ever, if you're willing to pay for it.