I don't think so. Who looks at design documents? Your own team. If you don't yourself catch that a change will cause problems with other teams, the existence of a design document won't magically alert that team. If you do suspect that there might be a bad interaction with another team, you can alert that team with or without a design document.

So again: how does a design document requirement help?

>Who looks at design documents? Your own team.

At least where I work, no. Your team, your manager, and anyone who you think will be affected, and depending on the scale of the change, you inform everyone that uses your tool or works on your product so that anyone can provide comments and feedback.

You're making the assumption that other teams and other leaders won't review your docs. In my experience, they do and always come back with more questions.

> If you do suspect ...

And that's exactly it. If I suspect something then of course I can communicate it directly or redesign, but we're trying to assess impact on areas I might not have no awareness of.

So let's put it in another way:

Design docs is one of many formal methods of communication in any organisation. It preserves context, change history, and a good part of risk management. It protects you and potentially saves downstream rework.