You keep skipping the law of economics....lower demand means higher price to achieve ROI. So few people would want such a niche product that all of the cost savings that you think you would gain with such a camera would be overcome by the prices needed to achieve ROI.
Also, this is 2020, I know a lot of people here might hate me for saying this but...stills are going the way of the 8 track player. The younger generation is growing up with YouTube, Netflix, HBO, etc. etc, and "influencers". They want to see, hear, and watch what is happening on their tiny cell phone screens. Stills are best enjoyed as prints or life sized displays; modern consumers don't print, they don't buy prints, and they have less than an 8sec attention span.
Camera manufacturers know all of this and they know video is more important now than ever; producing a camera without video is a sure way to fail. Most of my customers find me looking for stills, hire me because I also do video, and end up recommending me because I found a way to do both at their event or they decide their cell phones are good enough for stills and just want a "good video" to post on their social media of their birthday party, wedding, night out, graduation, ...insert activity here...
The other part you are skipping is that video is just a series of stills taken at some frame rate fast enough to not stutter...and compressed in a codec other than JPG. So yes, the architecture for video vs stills is nearly identical and as others have stated, the few additional audio components are negligible from a price perspective. I am quite sure if Canon or any manufacturer thought they could actually make money on a stills only camera they would have produced one by now.
If you want to look at what a video only camera looks like and the pricing there, then look no farther than the Cinema line to see what dedicated (read costly) video hardware actually looks like.
Yes. That's what I was trying to explain earlier. You target an established price point in a mature, well-known market, and you create a product to appeal to the broadest user base possible. If I can create a single product manufacturing schedule instead of two, I can lower costs on multiple fronts while increasing my profit margins and sales volume. Everyone wins. Stills shooters will have a fantastic stills camera. Video shooters will have a fantastic small body video machine. Everyone wins.