A while back there was a discussion about employee retention and churn, with some parties claiming a complete staff turnover over some period was a good thing, and that documentation could serve as the complete institutional memory. I hope they read this.
Writing and maintaining good documentation is hard, which in business terms means expensive. If a company doesn’t want to pay enough to reduce turnover it likely would not invest into documentation either. And even is it will no documentation would quickly turn a novice into a seasoned expert.