Yeah, I agree that initially, startups should focus on building value over lowering infrastructure costs.
But I'm continually embarrassed when companies who raised $100Mns in Series B funding continue to rely on AWS when they could have build out much sooner, and reduced their burn rate measurably.
Thing is, unlike the "get driven to work" analogy, programmers/etc are in the same problem domain as the required services.
It would be like a mechanic taking an Uber to his garage every day because he couldn't be bothered personally owning a car. What?!
"Car leases" (rented dedicated servers [possibly even managed]) are a happy medium everyone should consider.