About the <picture> syntax which the author finds great.

On the contrary, the srcset and sizes attributes on one image are hard to use. "So, we are left describing the all of the sizes that an element will be, across every breakpoint and container query, as a single string, in an HTML attribute. How disgusting."

A tool is neede to write media queries in the sizes attribute.

How is a tool supposed to generate (min-width: 1340px) 257px, (min-width: 1040px) calc(24.64vw - 68px), (min-width: 360px) calc(28.64vw - 17px), 80px though?

The author proposes to bury this attribute and use sizes="auto". The developer can rely on loading="lazy" to load the images after the layout is computed, thus the browser know the size in advance.
sizes values remain a must have for images displayed way up at the top of the page... well sizes="100vw" is a good fit for it, isn't it?
All other images? loading="lazy" sizes="auto"