* What’s being written down isn’t valuable, so people don’t trust the wiki to have valuable information and therefore ignore it.
* What’s being written down is valuable, but people have been trained to get information elsewhere and therefore don’t bother going to the wiki
I don’t really know how to address the former (“write better!” isn’t very actionable advice), but in my work I see the latter a lot, and the only way you can fix it is socially—if someone asks you a question that’s answered in the wiki, you have to tell them “read the wiki” instead of giving them the answer yourself.
People are lazy, and it’s almost always easier in the short term to just ask someone for the answer instead of looking it up yourself.