Many years ago, I took part in the development of a taxi-hailing mobile app that is still widely used today. I don’t know what kind of code they’re running now, but in those early days, the driver assignment code –if I remember it correctly– was similar in spirit to the grossly simplified example that follows. There are five levels of nested if statements in less than 30 lines of code. It doesn’t look so bad, some might say, but it’s not difficult to imagine how complicated this code can become with just a few more checks…
For me I have the habit of doing findFirst because determinism is important where I work. But I agree with you if determinism is not of importance.
I would only note that for the vast majority of my experience these streams can only return up to a single match. Determinism isn’t really preserved by findFirst, either, unless the sort order is set up that way.
Finding the first Jim Jones in a table is no more reliable that finding any Jim Jones. But finding PersonId 13579 is deterministic whether you findFirst or findAny.
Perhaps you work in a different domain where your experience is different.