Thanks, but what's the alternative when yarn relies on npm infrastructure? Like it or not, you're still using npm. It's got so you basically cannot do serious client-side development without one of them.
You're going to have to explain that better, otherwise you're just perpetuating that dumb lie.
You absolutely can do serious (whatever that means) client-side development without yarn or npm.
I've used them for fairly basic front-end JS development in mostly-Java projects. They worked fine. I don't know if they lack things you'd need to more involved work.