LP's in general, blind LP's included, for me are about the person playing. While I have never followed an LPer from their beginning, usually I learn about someone after they have become prominent, they usually have said they started for fun but since they were informative and/or entertaining enough to gain a fandom they just started doing more and like others have said you watch to see their experience.
To me a gameplay video is rarely about he game unless it has no commentary or purely informative commentary, such as a walk-through or a segment of gameplay. So for many Let's Plays the game is merely a Vehicle for seeing a personality you enjoy, and are able or relate or contrast to yourself based on how they react to the game they are playing.
Also like others have said, it is a preview of a game you might want, OR if you weren't that interested in it before but like the Let's Player and watch it, you may be sold on the game from their series.
To me a gameplay video is rarely about he game unless it has no commentary or purely informative commentary, such as a walk-through or a segment of gameplay. So for many Let's Plays the game is merely a Vehicle for seeing a personality you enjoy, and are able or relate or contrast to yourself based on how they react to the game they are playing.
Also like others have said, it is a preview of a game you might want, OR if you weren't that interested in it before but like the Let's Player and watch it, you may be sold on the game from their series.