I think this will depend on the industry. Slow vs fast moving, regulated vs not, whether someone depends on your API or not, etc.
But regardless, having had to deal with some legacy code written 10 years ago by someone who isn’t working at the company anymore, I would take an outdated spec over none at all. At least then I know what people intended back then, what they cared about, what they had and hadn’t considered. As long as the spec is written by a human, that information is surely valuable.
I think this will depend on the industry. Slow vs fast moving, regulated vs not, whether someone depends on your API or not, etc.
But regardless, having had to deal with some legacy code written 10 years ago by someone who isn’t working at the company anymore, I would take an outdated spec over none at all. At least then I know what people intended back then, what they cared about, what they had and hadn’t considered. As long as the spec is written by a human, that information is surely valuable.