Then that person is doing all the legwork, but someone else can come along and create a KB themselves with those answers.

Fix your group's culture. Document things. If people refuse to document things, then do it for them and shove your docs in their face. Do it until they write the documentation themselves.

> Fix your group's culture.

Culture-change is about the hardest thing to achieve.

It's also the most important thing. If your culture is bad, changing what tool you use isn't going to fix everything. You're just going to have a new tool everyone uses poorly.