- It eliminates one way of forging results. Without stating the seed, people could consistently fail to reproduce your results and you could always have "oops, guess I had a bad seed" as an excuse. You still have to worry about people re-running the simulation till the results look good, but that's handled via other mechanisms.

- Many algorithms are vastly easier to implement stochastically than deterministically. If you want to replay the system (e.g., to locally debug some production issue), you need those "stochastic" behaviors to nonetheless be deterministic.

- If you're a little careful with how you implement deterministic randomness, you can start to ask counterfactual questions -- how would the system have behaved had I made this change -- and actually compare apples to apples when examining an experimental run.

Even in your counterexample, the random seeds being reproducible and published is still important. With the seed and source published, now anyone can cheaply verify the issue with the simulation, you can debug it, you can investigate the proportion of "bad" seeds and suss out the error bounds of the simulation, etc.

> It eliminates one way of forging results. Without stating the seed, people could consistently fail to reproduce your results and you could always have "oops, guess I had a bad seed" as an excuse.

Why does this matter? If people consistently fail to get results similar to yours by using different seeds, your results are invalid whether or not you made them up. And if people consistently do get results similar to yours with different seeds, your results are valid whether or not you made them up. No?

> Even in your counterexample, the random seeds being reproducible and published is still important.

> you can investigate the proportion of "bad" seeds and suss out the error bounds of the simulation

How does publishing seeds help with that? You do that by examining different seeds. If you know what seeds were used in the paper, this process doesn't change in any way.