"Working by accident" is still "working" though, so from the standpoint of the person using it, the reason doesn't matter. I'd also argue that the main point made above about docker wasn't that it's reliable, but that it gives developers more feedback when trying to work with it. For people who's goal isn't just to consume builds but write their own, existing Nix builds being deterministic does nothing to help them if trying to modify or borrow parts of them leads to issues they can't easily fix.

I think Nix fits a pattern that's happened in plenty of other domains where the technology that focused on doing things "right" failed to win out against a competitor doing things "wrong" but optimizing for a lower barrier of entry. The logic that a perfect solution is worth an up-front cost is compelling, since having an imperfect solution has a long-term cost that never goes away, but this misses the fact that pushing the cost until later has value of its own; making things easier today at the cost of tomorrow buys time to improve things before the cost is incurred.

At the risk of a convoluted metaphor, imagine that someone moves into a new house and calls two plumbers asks them to hook up the water in their bathroom. The first plumber says that they can get it done so the bathroom can be used today, but they'll need to come by again in a week or two since they might need to make additional adjustments. The second plumber says they've come to with a way to make sure that they never need to come back to make adjustments, but it will take them a full week to finish setting it up before anyone can use it.

For most people, it doesn't matter if the second plumber's solution will be better next week if they need to use the bathroom today, as long as the first plumber's solution can last long enough before it needs to be fixed.