You're kind of getting into a philosophical question of what makes a video game an actual video game versus some other form of entertainment. Personally, I think the most important part of a video game is that it captures a very unique and personalized experience for the player (primarily through interaction). We actually have several genres of 'video games' that aren't really much a video game - Visual Novels being one, as well as Telltale's Moviegames. These are still absolutely valid forms of entertainment, and there's sort of an unspoken disdain for these kinds of games being streamed.
A game can absolutely be a storytelling tool, but if its only claim is as a storytelling tool (ex. The Beginner's Guide, Gone Home, Firewatch) then given current culture the developers should expect that it won't be respected as much... With the modern sharing culture, a lot of plot gets spoiled in video games that are far more respected in other mediums. Undertale is a good example here - the dichotomy of pacifism vs. genocide was so heavily spoiled throughout the fanbases almost instantly, even though the understanding of that is one of the most important parts of its storytelling (as a unique, interactive device to the player).
JRPGs are a heavily story-driven genre, and modern JRPGs usually have other aspects to make sure they remain an interesting and unique experience for the player - FFXV is open world, Disgaea 5 has a ton of crazy post-game shit. While I don't know about Persona 5, I can guess from what I know of earlier games that the story is the main focus of the game and if they removed a lot of what made the earlier games unique (mostly the insane amounts of grinding) then there's not much to draw people in to play it when they could watch it instead.
It's also important to note that modern sharing culture is itself a form of advertisement. A lot of games flourish thanks to streaming and YouTube that otherwise probably wouldn't have. However, when you have a game like The Beginner's Guide where the difference between playing and watching a 2-hour YouTube video is almost non-existent, then yeah, it's going to undermine sales a little bit. Whether this is acceptable from gaming culture or not is a different bag, but I argue that pretending interactive media is like a video game is causing problems itself.