What's your take on grid? I still can't quite grok the algorithm - but from your article, your proposal seems really similar to what's available with grid.
Grid does suffer from not being able to set min/max track sizes - like have a sidebar be say 20% of the width, but clamped between 200px and 300px
It is not that simple. In common case that's an LP task. It can be reduced to O(N) in some cases but in worst case it has polynomial time-complexity.