Earlier quoted context omitted.
> setting breakpoints allows some sanity in the build and testing process otherwise you have an infinite scope for issues which of course would be pretty lucrative for a boutique agency. Honestly, now that container queries are available, I see very little use for breakpoints. Container queries allow for easy reuse of components, and a truly fluid and responsive design.
IMO the promise of container queries isn't that breakpoints will go away, but rather that breakpoints can emerge from the bottom-up composition of components rather than top-down from your CSS framework or Tailwind config or whatever. You're still probably going to want the left sidebar of your multi-column layout to collapse behind a menu on narrow viewports and abruptly appear when the viewport width gets to >= n […
The example you give of a sidebar collapse with a menu button replacement can easily be accomplished with a container query on the wrapping box, no?
I'm honestly curious about a use case that a media query breakpoint can handle, but which a container query can't.