It is not well known but there have been numerous scandals which put this trust into question. For example in 2012, a trustee of the Wikimedia Foundation UK used his position to place his PR client on Wikipedia’s front page 17 times within a month. Wikipedia founder Jimmy Wales made extensive edits to the article about himself, removing mentions of co-founder Larry Sanger. In 2007, a prolific editor who claimed to be a graduate professor and was recruited by Wikipedia staff to the Arbitration Committee was revealed to be a 24-year-old college dropout. These are only a few examples, journalist Helen Buyniski has collected much more information about the the rot in Wikipedia.
I don’t really understand how decentralization would address the trust and legitimacy problems of Wikipedia. I do see value in adding community wikis to Lemmy, however.
I wouldn’t really compare Bluesky to Mastodon. Ultimately, the Bluesky team still has control over what’s allowed on the app and what’s allowed on the network until third parties launch their own AppViews and relays.