Just to point out that I was pointing out only one specific example of a document (where I recently encountered this) that used section numbering references.

It's not the only one, it's all over.   This isn't just "if it hurts when you do that, don't do that" after the fact kind of advice that is required; we need a stronger statement somewhere that clearly says that external references to the spec must not use just section numbers because they will change.

Andrew's suggestion is a good one - but it needs to be communicated.