It radically simplifies everything. Every commit is reproducible across the entire tool chain and ecosystem. It makes the entire system kind of pure-functional

It radically simplifies everything. Every commit is reproducible across the entire tool chain and ecosystem. It makes the entire system kind of pure-functional and stateless/predictable. Everything from computing which tests you need to run, to who to blame when something breaks, to caching build artifacts, or even sharing workspaces with co-workers. While this could be implemented with multiple repros underneath, it would add much complexity.