yarn 2 solved real problems with zero install and advanced PnP. Maybe the only problem was that it was released too early, wasn't mature enough when it came out. Now it's just better than v1 and npm, works particularly well on large mono repos where upgrading a package can often break other modules due to how node_modules hoisting works.
The problem with Yarn 2 is that it wasn’t Yarn. You can’t change the whole thing and keep the same name. They thought people would just keep using Yarn out of inertia. That’s not how it works.
Eh. They're allowed to do that as per a literal definition of semver, but they turned it into a completely different tool with completely different usage patterns and use cases. It's one thing to have to make some small tweaks to handle an isolated breaking change in a dependency. It's another matter entirely to have a perfectly good core part of your stack deprecated out of the blue and told that you need to rewrite every line of code that it touches.
I see this as analogous to the Angular 2 situation, except that Google actually did a good job maintaining Angular 1 (retroactively named "Angular.js") for a number of years afterwards and providing a solid migration path. Everyone who had staked their projects and businesses on the future of Angular 1 was understandably annoyed.
All that being said, while I have problems with specifics of their approach, I actually think Yarn made the right call on this. After NPM caught up with v7, it became a bit of a wasted effort to have two redundant projects that were almost drop-in replacements for one another. Yarn staking out a different path at least justifies its continued existence.
What I think could have been better is if they'd put an explicit acknowledgement in the migration docs that Yarn 2 wasn't going to be a good fit for all users of Yarn 1, and a recommendation of NPM 7 as an alternative successor to Yarn 1 for such users. An even nicer gesture would have been if they'd written an alternate migration doc for Yarn 1 -> NPM 7.
