I think it was made for publishing scientific research, and you could flag the options for what you wanted checked. If you were okay without the passive voice hints, you could still make whatever you were writing very direct and concise, or less wishy washy.

This is wrong. It's a good rule of thumb because passive voice can be a common indicator of weak writing, but it has plenty of good uses in strong writing. The best case to apply it is when the object of a sentence was previously a subject or other focus of prior sentences, and so is more familiar to the reader than the subject of the new sentence. For example:

"The United States had maintained neutrality until 1941. However, it was attacked at Pearl Harbor, and then chose to enter the war."

"The United States was neutral until the Japanese attacked Pearl Harbor in 1941, leading them to enter the war."

I'd say active is still better here.

I would disagree. This sentence is about the Unites States, not Japan, and the use of passive voice reflects that.

This is disingenuous. Removing the bad actor in this sentence removed part of the cause for the effect. Not an attack happened, a japanese attack happened.

I you feel that the actor is an important part of the sentence, you can include it in passive voice as well: “However, it was attacked at Pearl Harbor by Japan, and then chose to enter the war.”

How and why is that possibly better than saying "the Japanese attacked them at Pearl Harbor"? The passive voice is what enables the omission of the actor.

Could also just say "the attack on". Then you don't shift focus or use the passive voice.

It's extremely important in a lot of policy positions to be able to use things like "a decision was made".

An example of this is when collecting and summarizing anonymous feedback.

Is it extremely important to omit who made the decision?

Yes. In this case "good" writing is bad writing because the author's goal is obfuscation.

It's bad writing for the reader. But lots of writing isn't actually for clear communication. Especially when the government is involved.

If one wishes to maintain continuous employment? Yes.