Our 'workspace' is so ornate that yarn couldn't handle it. 1.21+ almost looks right, but something very bad is still going on with mocha deduping, such that tests are failing with really bizarre error messages.
I check yarn about every three months, or when I find a new, infuriating bug with the npm CLI (so, every couple of months on average). I think npm install suffers greatly from not having a formal spec. It has been bugfixed by so many different individuals now that it has reached a truly astounding level of schizophrenia.
If yarn didn't exist, I would have started trying to break down the install problem into many independent concerns that can be reasoned about individually and tried to solicit help in making a full installer out of it. If I'd known I'd still be trying to make yarn workspaces work for us 18 months later I probably would have.
Node modules in general have some bad patterns of delegation that are utterly antagonistic to self-documentation, and both yarn and npm seem to suffer from this as well. I think in the next week or so I'm going to have to set up a small test case that exhibits the yarn bug I'm seeing, or any of the half a dozen interlocking (emphasis on 'lock') npm bugs that now have me painted into a very tiny corner.