[mrkeen]

> It's trivial and it doesn't matter

They are different and they absolutely do matter.

DateTime.Now() is a perfectly valid thing to write while coding. Unless you are in a distributed system, where 'now' doesn't exist, so all source code using 'DateTime.Now()' is automatically suspect. How do you know if you're in a distributed system? That's a programming question, not a coding question. And from a lot of the microservice push-back you get here on HN ("just use a single DB instance - then your data is always consistent",) a lot of devs don't realise they're in a distributed system.

"Backtracking", "idempotent", "invariant", "transaction", "ACID", "CAP", "secure", "race condition", "CRDT", are all terms that exist at a programming level, but they don't show up in the source code. A single effectful statement in the source code can be enough to break any of these quoted programming terms.