I think of cloud platforms as less complex than managing your own systems. It's trivial to go from zero to functional product on GCP or AWS, and it's honestly not very expensive to get started either. GCP and AWS very clearly subsidize costs for early-stage startups in an effort to lock them in. A tiny startup might have a cloud hosting cost of 3 figures a year until they really take off.
And when your product does take off, scaling is often trivial.
Yes, scaling is trivial on AWS if you rewrite from scratch 3 times and rearchitect 4 times, but at least you don’t have to enter your credit card number twice.
His assumption is that you're familiar with cloud design patterns. So if you know what you're doing, costs are manageable and scaling is a breeze, that's what the cloud was literally designed for.
I just don't see this. Building what I am describing can be done in days sometimes hours. Where exactly is the time and complexity? I would be willing to bet given a true greenfield(e.g. I can't use an ansible script that stole from my last job) I can build an autoscaling flask app with CI/CD and local environment on ECS twice as fast as accomplishing a lesser facsimile with a bare metal server or a VPS. If I built on a VPS I would still have concerns like backups, High Availability, DNS, Networking, etc. etc. to deal with.
And when your product does take off, scaling is often trivial.