I agree that this makes sense for a lot of people. E.g. I have clients that I recommend use AWS simply because hosting is a small cost item for them and it isn't worth their effort to optimise it for cost (at least not until they grow huge) vs. spending effort elsewhere.

Moving to cheaper services quickly becomes a big deal for people with low margins and high infrastructure costs, though, where moving to cheaper infrastructure can make the difference between being able to match competitors on price or not.

The key is to understand your hosting needs well enough to know whether or not you can afford to build a dependency on AWS specific services.