Any answer we can give here will be purely speculative until the miserable miscreants reveal their own rationales.

In skimming the query, I can really only conclude that the issue might be one of your style of presentation. As originally written, it was as has been said, a wall of text.

• Walls of text are unpopular because we have to slog through them. This demonstrates that you don't know how to present your ideas.
• Your writing style is also slightly jocular and slightly careless: too many uses of words like "dealio" and "thingy". It demonstrates that you don't care enough to learn what the "dealio" is actually called, with the result that a respondent might not care enough to bother answering.
• Your query is about twelve times as long as it needs to be. It basically boils down to Would a set of guns mounted 180deg apart on a rotating platform as per the design sketch be a viable design for any type of weapon (handheld, emplacement, or vehicle mounted)?

It's not that long questions are inherently bad. It's not that jocular wording is bad. It's not even that long-winded presentation is (necessarily) bad. It's just that, in my opinion, the perfect storm of all these things, and possibly others, ticked a couple readers off enough to downvote your query.

That said, stylistic issues aside (which I think you could profitably edit away), I honestly don't find your query to be either useless, unclear, or particularly lacking in research. (Those are what we consider especially valid reasons for downvoting.) Thus, I wouldn't downvote. Though I wouldn't necessarily upvote either! And that's a different matter.

Any answer we can give here will be purely speculative until the miserable miscreants reveal their own rationales.

In skimming the query, I can really only conclude that the issue might be one of your style of presentation. As originally written, it was as has been said, a wall of text.

• Walls of text are unpopular because we have to slog through them. This demonstrates that you don't know how to present your ideas.
• Your writing style is also slightly jocular and slightly careless: too many uses of words like "dealio" and "thingy". It demonstrates that you don't care enough to learn what the "dealio" is actually called, with the result that a respondent might not care enough to bother answering.
• Your query is about twelve times as long as it needs to be. It basically boils down to Would a set of guns mounted 180deg apart on a rotating platform as per the design sketch be a viable design for any type of weapon (handheld, emplacement, or vehicle mounted)?
• Per T. Sar's comment, some users immediately downvote something that is made to entertain a silly idea instead of actual stuff that can be used in creating a piece of fiction. The "Just a random idea I had" might be enough to trigger this instinct.

It's not that long questions are inherently bad. It's not that jocular wording is bad. It's not even that long-winded presentation is (necessarily) bad. It's just that, in my opinion, the perfect storm of all these things, and possibly others, ticked a couple readers off enough to downvote your query.

That said, stylistic issues aside (which I think you could profitably edit away), I honestly don't find your query to be either useless, unclear, or particularly lacking in research. (Those are what we consider especially valid reasons for downvoting.) Thus, I wouldn't downvote. Though I wouldn't necessarily upvote either! And that's a different matter.