Tooling like npm, cargo, and others existed well before uv came up. I have used poetry years ago, and have had reproducible virtual environments for a long time. It's not like uv, at least in that regard, adds much. The biggest benefit I see so far, and that is also why I use it over poetry, is that it is fast. But the benefit of that is small, since usually one does not change the dependencies of a project that often, and when one does, one can also wait a few seconds longer.