If you want to dynamically provision storage or grab an extra instance when you’re under load or something. It’s handy to not have to sit on a bunch of storage you’re not using just in case there’s a rush.

Unless the storage (or compute) is so cheap that it's cheaper to just always have enough on hand than bother with autoscaling and the added complexity and potential point of failure.

Old-school dedicated servers are so cheap that you can match a startups' peak autoscaled load and still pay less than their "idle" load.

Exactly my case. My peak load costs are way less than their "idle". Storage expansion if needed is even simpler to handle. Those cloudy people like to create problems where none exists.