I do see what you're getting at but in the SQL case an unhinted statement can potentially produce such a terrible plan it invariably times out and triggers a 50

I do see what you're getting at but in the SQL case an unhinted statement can potentially produce such a terrible plan it invariably times out and triggers a 500 from the service making the query. This sort of thing somewhat blurs the boundaries between affecting performance and affecting behaviour. I'm not claiming that there's an obviously right answer here, only that there can be more questions about whether something is a good idea on net than people always consider. Note: It would not surprise me to find that the actual motivation for leaving comments out of JSON went something like: 1) We can't have line comments because we don't want to be newline sensitive that way 2) If we do /* ... */ style comments people -will- write incompatible parsers for them no matter how carefully we specify them 3) Argh but I wasn't there at the time, so the question will have to remain open.