When you view any page's history, all you get is a list of pseudonyms and IP addresses. Sure, you can probably get the country of origin and sometimes maybe even the employer from the latter, but that's basically it. I don't think that's very much, given that nobody on Wikipedia is required to disclose who they are in real life (there's even a policy specifically against posting such information about others[1]). Well, okay, in theory users with a financial conflict of interest in a topic are required to disclose it, but in practice PR agencies can often get away doing anything to articles about their clients.
And openness in itself doesn't guarantee reliability anyway. OpenSSL being open-source didn't prevent Heartbleed from happening. The so-called "Linus's law" is often a mere vacuous truth; there's rarely enough eyeballs to make even the most obvious bugs shallow. And eyeballs themselves don't help if they keep looking in the wrong places.
The problem with Wikipedia isn't merely that it may be sometimes inaccurate. It is that its sources of inaccuracies are much more numerous, most rather predictable, and yet next to nothing is done to address that. A book written by a single author may also be inaccurate; but I'd be more inclined to believe a book written by someone 0) whose good reputation is at stake and who therefore has an disincentive to actively misinform (sometimes at least), and 1) who has an editor above them watching out for inconsistencies; rather than a bunch of pseudonyms and numbers that can immediately publish anything they think up with basically no oversight. Trustworthiness is a spectrum, and Wikipedia does significantly worse on it than many other sources. Review processes on Wikipedia are overworked and even those focus mostly on style rather than substance. There are some relatively sensible policies enacted, but they are quite vague (and therefore bendable to ever-changing whims of particular users) and selectively enforced. And don't get me started with the dispute resolution processes...
There is no systematic, consistently applied process to ensure Wikipedia's accuracy. It is addressed just like the gun problem is in the US; it proceeds from one outrageous incident to another[2], with everyone barely applying ad-hoc measures after the fact, while the people who do have the power to make a real difference are either in complete denial that this is a problem at all or are too attached to the idea that the foundational laws can never ever be wrong to actually enact meaningful reforms.
[1] https://en.wikipedia.org/wiki/Wikipedia:OUTING
[2] https://en.wikipedia.org/wiki/Wikipedia:List_of_Wikipedia_ho...