I believe what you're saying is true, I just haven't seen it in practice. I've long joked that the best documentation is the source code, and, really, it's not so much a joke as a truism. I've found that having readable code has resulted in the best documentation I've seen, and you don't have to worry about it being out-of-sync!
I do believe documentation is important, but, having joined recently the largest corporation I've ever been a part of where I work on products of a larger size than ever, I am amazed to find documentation here to be as bad as, or even worse, than anywhere else I've worked, and most of it is simply outdated and irrelevant. I guess I need to work somewhere that does documentation well to believe in it more.
I also consider myself a good technical writer. Unfortunately, it seems that many software developers don't share this skill, and this could be a major reason why so many resist writing it. I think a litmus test for this is whether someone prefers to share information via a document, or via an in-person meeting, a conference call, or a video recording of a meeting. Unfortunately, videos and meetings are not searchable, indexable, updateable, or quick to scan. But they seem to be preferred by the same people who don't want to write anything down.
I've used that strategy a few times now, albeit mostly with "user" facing docs where the users were other developers. My current company is tiny but I wrote both internal and user facing docs from day one, so practicing what I preach. It's pretty useful. Writing stuff down is permission to forget and I often end up consulting my own docs, especially for procedures that only happen occasionally.
In prior projects I did it too and success was mixed. On one hand, the docs we got out of it were objectively great, as in, users complimented us on the docs regularly, they were a source of competitive advantage and we could tell they worked because users would regularly show up successfully using advanced features of the product without having asked us any questions.
On the other hand, creating a self-sustaining docs culture was hard. People would do it when faced with the expectation of doing it, and often the resulting docs were fine - tech writing isn't as hard as it's sometimes made out to be - but getting other devs to really buy into it and become docs evangelists themselves was much harder. Also of course you'd have inevitable team friction when someone really hated writing stuff and would have to be forced to do it, and then they'd submit min-viable or low quality work. No different to having a team member who refuses to write tests, of course.
I think this can be solved with time, with cultural change in the industry. One problem, and please don't take this personally because I'm talking really generally here, is the view that source code is as good as documentation. I feel like lots of devs convince themselves of this because they like writing code and don't like writing docs, but I never found it to be true in practice. Any time I have to use an API or tool that has tons of missing or obsolete docs my heart sinks, partly because rummaging through source code is slow and tiring compared to reading a well written document, and partly because it tends to be a proxy for low effort work in other ways. The claim that docs are always obsolete is self-fulfilling. If you don't put in place procedures to ensure they're kept fresh and good then they'll rot, and then that's used as a justification for not putting in the effort, so it's a vicious circle. Again by analogy to testing, competent teams don't just let devs comment out tests instead of updating them, it's just not culturally accepted in high-functioning environments. Same can be true of docs.
I do believe documentation is important, but, having joined recently the largest corporation I've ever been a part of where I work on products of a larger size than ever, I am amazed to find documentation here to be as bad as, or even worse, than anywhere else I've worked, and most of it is simply outdated and irrelevant. I guess I need to work somewhere that does documentation well to believe in it more.
I also consider myself a good technical writer. Unfortunately, it seems that many software developers don't share this skill, and this could be a major reason why so many resist writing it. I think a litmus test for this is whether someone prefers to share information via a document, or via an in-person meeting, a conference call, or a video recording of a meeting. Unfortunately, videos and meetings are not searchable, indexable, updateable, or quick to scan. But they seem to be preferred by the same people who don't want to write anything down.