this is not at all an unproductive direction, in fact i personally think it is a very productive thing to talk about (at least as a library author) and the only reason it is not talked about more is because someone still has to write the smaller, more modular frameworks to replace Foundation, and we do not always have time to take a 3 week detour to write a pure swift library so more often than not we just go down the Foundation route because it is the path of least resistance.
the issues with Foundation are well known and if anything i think the things you have mentioned are only touching on the tip of the iceberg.
again i do not think anyone disagrees with what you are saying but it is a very big task and “i hate Foundation” is necessary but not sufficient. in particular many of us pure swift library authors are not good at cocoapods or XCode so writing libraries that don’t import Foundation but only compile on amazon linux and only compile on this week’s nightly toolchain is not a step forward it is really just more of the same if we are being honest.
if we want to make progress it is important i think to focus less on “we need more foundationless libraries” because there actually are a lot more than people think but they don’t get adoption because going from linux to macOS/iOS/watchOS/tvOS is just as hard as the other way around and the ecosystem is still fragmented just in a different way.