So, firstly, your initial explanation is perfectly grammarian, and very clear. But as you correctly say, then we leave the world of grammar. But it's not correct to say that we then see this construction taken further, because it isn't the same construction at all.
That is where I find myself trying to understand the common law usage of the term "passive" when applied to writing or articles in the press etc. Things that are grammatically passive or active are definably so whereas things that are claimed to be "active" or "passive" accounts of events are by definition subjective and usually haven't got all the text or context.
I used to struggle with this in my former life as a writer and frequent flyer on American creative writing websites, where I was forever instructed to write "actively" and to avoid "passive writing" - which had sweet f.a. to do with passive or active voice but was based entirely on well meaning but completely subjective and unqualified definitions of what actually constituted active or passive writing. I came to the conclusion, and it seemed to be supported by grammatical rules, usage and common sense, that a lot of people who didn't know enough to give advice, gave the advice anyway.
Voice is very simple.
@jefmcg explained it above and anything else is made-up. Although there ought to be a subjunctive voice in English if there isn't already, would that there were. BB