The political slant is anything but blatant, because all of the complaints focus on Republican/Democrat wedge issues where both sides are conjuring alternate realities to sell to their bases like soap operas.

The real political slant is put on Wikipedia by governments and companies that are willing to consistently employ people to cultivate and maintain bias (and to provide the technical support to prevent them being easily caught.) They make sure certain things aren't mentioned in particular articles i.e. when they are added they delete them, and when those deletions are controversial, they take advantage of the pseudononymous voting system. They reinsert untruths (and in the worst cases can even commission references for them.) They pay attention to articles that are rarely visited by experts, or rarely visited at all, to make sure that when the article subject is in the news, the first facts that people find are friendly facts (which then shapes the news coverage, and an instant POV for lazy pundits.)

The public really has no chance against this; the only time that bad actors run into serious difficulties is when they encounter their own counterparts, working for their enemies.

Wikipedia's failure mode is the same as Reddit's, or any other forum that allows anonymous control over content or moderation. It's cheap for hugely resourced governments, companies, and individuals to take it over. The price of one tank would keep a thousand distortions on Wikipedia indefinitely.

What about political biases of those who publish traditional encyclopedias?

So it's it's six of one and half a dozen on the other side? Not much evidence of that.

Mediabiasfactcheck.com says 'These sources (Britannica) consist of legitimate science or are evidence-based through the use of credible scientific sourcing. Legitimate science follows the scientific method, is unbiased, and does not use emotional words. These sources also respect the consensus of experts in the given scientific field and strive to publish peer-reviewed science. Some sources in this category may have a slight political bias but adhere to scientific principles'

On the other hand, https://www.newsmax.com/us/wikipedia-liberal-activist-websit... outlines some serious problems with Wikipedia. Here's one.

'Established leftist outlets The New York Times and BBC News are the most cited sources, around 200,000 stories. The Guardian, an equally left-wing outlet, is cited third at almost 100,000 citations'. Among the top 10 most-cited, only one was right-leaning.

Though it is worth noting that they conclude

> The bias on a per word basis hardly differs between the sources because Wikipedia articles tend to be longer than Britannica articles.

If reality has a left-wing bias, then you still have to control for that confounding effect.