This is kind of a different topic for me, so if my information is off-base, please forgive me and give me proper sources below.
Let’s Plays: I cannot think of a more decisive topic in my house. I think they are fantastic, my dad thinks they are a waste of time. He wonders why I am willing to watch someone play a game for a day worth of video as opposed to play the game myself. I get it, I really do.
My reason for watching someone play a game comes to only three reasons. The first of which is I am always broke. It would be fantastic if I had all of the money for every console and game that my heart desires, but I do not even break cost of living most months. Seeing how most games that hold my interest are either 70+, or on a console that I don’t own (see the Switch), I have no ways of actually playing said game. The only way I can experience it is by watching others play it. Most Let’s Play(ers?) already play in a similar way that I do: they search all of the dark corners for hidden bits of lore. That is a (mostly) free way I can get the entertainment that I crave.
The second reason is time. Most games that I want to play (Persona 5, for instance) take hours, if not days, to finish. With the cavalcade of games that come out every quarter, I do not have even a quarter of the time required to play everything. Throw in old games, open-ended games (Minecraft, Terraria, Grand Theft Auto) and games that piggy-back off of older titles (Life is Strange) and I would not have time to sleep or eat, let alone write. Watching someone play for an hour while describing the lore surrounding the areas that peak my interest satiates that part of me that craves all the games.
The third reason is just simply skill. For instance, I love the concept of the Dark Souls franchise. I own all of them, and I have put dozens of hours into each. I am not good at Dark Souls. I have put the dozens of hours into them and die incredibly quickly, sometimes not even being able to get out of the first place. They are made to be very hard. Part of why I love them is that they do not hold the players hand and refuse to guide anyone to anything. I still love the atmosphere, art, and worlds of these games. I can ONLY experience these games through a third party.
For these reasons, and I’m sure that I’m forgetting more, I love Let’s Plays. I get my shots of lore, as well as get to experience the parts of games that I would love. I still play games like Tetris or Hearthstone myself, because watching someone else play would just frustrate me (Everyone has their own way of being “good”).
I have not done the research, but I am curious how Let’s Plays effect game sales in the long term. I have a pretty good feeling that the explosion of popularity for Minecraft was partially fuelled by groups like The Yogscast, but I remain ignorant to if Atlas’ refusal to allow anyone to publish gameplay of Persona 5 has effected longterm sales.
Let’s face it, anyone who wanted to know anything about Persona 5 has bought Persona 5.