Nowadays for customers spending millions of dollars you'd expect (at least, Amazon would expect) that the customer has a FinOps department who are already working on getting the most 'bang for their buck' out of what they're paying for and minimising their spend, and they would jump to another platform in a heartbeat if they thought they could save money. It's not unreasonable to think that you don't need to do these customers any favours to keep their business, because those customers are big enough to look after themselves.

For smaller customers, the friendliness of customer support and the flexibility to help them if they make mistakes is much more likely to be a retention consideration. And who knows when a company spending 3 digits a month becomes a customer spending 6 digits a month? You want to be the provider of choice in case the company grows.