[jorams]

Bespoke version soup is unsustainable, but part of why people keep doing it is that it tends to work fine. It tends to work fine in part because OS-level libraries come from a different, much more conservative world, in which breaking backwards compatibility is something you try to avoid as much as possible.

So they can take a stable, well-managed OS as a base, use tools like mise and asdf to build a bespoke version soup of tools and language runtimes on top, then run an app on top of that. It will almost never break. When it does break, they fiddle with versions and small fixes until it works again, then move on. The fact that it broke is annoying, but unimportant. Anything that introduces friction, requires more learning, or requires more work is a waste of time.

Others would instead look for a solution to stop it from breaking ever again. This solution is allowed to introduce friction, require more learning, or require more work, because they consider the problem important. These people want Nix.

Most people are in the first group, so a company like Railway that wants to grow ends up with a solution that fits that group.