Many ecosystems haven't gotten past the "single dependency file and lock file" system where an entire project has to use a single version of each dependency. There are people splitting their project into a thousand "microservices" and making them interoperate over HTTP instead of regular function calls so that each part of their project can have its own dependencies.
And while I have been using development snapshots for years with my system and didn't have more bugs to cope with compared to other systems, I can understand that developers in corporate contexts need to be able to specify dependencies with versions. So I appreciate that proposal very much and hope it will lead to a better solution for every body involved by providing a way to use versioned dependencies without introducing too much overhead for those who don't need versioned dependencies.
No package manager can fix a cultural problem.
Meanwhile, I've heard people spend ages complaining that this is totally wrong...while overseeing setting up local artifactory instances and wrangling proxying to do the exact same damn thing.
Perhaps they shouldn't go past that.
multiple library versions is one of the lowest priorities when doing micro services id say
this is not to say that people don’t significantly over use micro services, but there are plenty of hard problems they solve