Xournal++ is a nice tool for that.
This document talks about the issue.
As of now, it does leak metadata, as already mentioned by other users, but they’re working on fixing that. The pinecone overlay network is a step towards that. A further extension to protecting user metadata they’re planning on taking is routing the messages over TOR.
The main issue is that it needs to be verifiable. If you do original research and write on the basis of your own knowledge, there’s no (easy) way for anyone else to verify that what you wrote is true. The trust is on that one person who claims to have experience with what they wrote.
@Niquarl@lemmy.ml mentioned the second main issue which is bias. If you’re writing about a topic that is close to you that has multiple viewpoints, what you’re writing is most likely going to be biased toward that view. Wikipedia can’t just have “the truth” about a topic that people disagree about through consensus. It’s job is to only list the different viewpoint and to tell how prevalent those viewpoints are.
If the topic is notable, you’re likely to find a good source that talks about that topic, if you can’t find a source for that (regardless of how true you think that fact is), then too bad.