I think there is some value to MBFC, even though there are also cases where it is problematic - I don't think a blanket rule would be right.

The issues (& mitigating factors):

• Some of the 'mostly analytics' sources still have 'bias by omission' problems or misleading headlines, even if the facts in the articles are accurate. But I think on the fediverse, we aren't beholden to algorithms or their editorial choices in terms of the balance of what we see, so the impact of this is limited.
• Opinion pieces have a place, although arguably not on World News. At the very least, factual pieces from outlets that also publish opinion have a place. But MBFC downrates outlets for having an opinion at all even when clearly labelled as such.
• The attempt to categorise every bias on a left to right scale when really there are so many dimensions any bias could be along isn't as helpful.

So I'd suggest:

• Only mentioning it when an outlet has a history of publishing things that are factually incorrect (or there is reasonable doubt over it). Not every fact can be verified from first principles (and sadly often articles don't name their primary sources - in a better world having no source would reduce credibility, but it is often hard to find articles that meet the well-sourced bar). People deliberately muddying the waters create think-tanks to cite with fake facts, fake scientific journals, and cite other unreliable sources - fact checking often requires on the ground investigation, asking reliable experts, and so on; it is simply impossible to be in expert in everything you read in the news to spot well-executed fake news. I think of the approach like a tree - there are experts in an area who can genuinely apply critical analysis to decide if something is fact or bogus. But there are also bogus experts. Then there are aggregators of facts (journals and think-tanks, etc...) that try to only accept things reviewed by genuine experts. But there are also bogus aggregators. Then there are journalists and outlets that further collect things from genuine aggregators and experts, and refine them. But there are also bogus outlets. Sites like MBFC try to act like a root to the tree and help you identify the truthful outlets, who have a good record of relying on truthful aggregators, who rely on truthful experts.
• The left / right bias part means very little - I'd suggest ignoring it if you're looking at a single article.
• Any of the higher tiers of factual reporting should be fine and not worth a mention.

If there are reliable sources countering some facts, posting those instead of (or as well as) complaining about the source is probably better.