Agreed on a lot of this, but I'd be cautious about saying that any kind of documentation is "simple". Especially when it comes to technical products - be they internal or external.
Technical writers train specifically to communicate complex technical topics to readers, and it's not an easy job. It requires understanding your readers, what kind of backgrounds they have, and what are they trying to achieve. This becomes especially important for documentation that is meant for your customers, where very real revenue depends on the quality of your docs.
I'm a bit biased since I'm the founder of a documentation startup [0], but tools also do play a big part. Devs often tend to enjoy writing something Markdown next to their code than going to an old wiki like Confluence that's disconnected from the engineering cycle. Choosing the right tool lowers the barrier to keeping the docs up to date.