I've seen an article recently whereby a developer suggests it does. I don't really agree so thought we could have a discussion on it and let people have a say themselves.
I think it can be bad for very linear games like visual novels because if you watch a playthrough, there's not a lot left to encourage you to play it. However, for non-linear ones I think it can be good just to showcase the game in a different light. This is why I like streaming and watching Nuzlockes, because every run is different and memorable.
Multiplayer games are definitely more popular on Twitch but I wouldn't say its exclusively for that. Also claiming that Twitch has killed single player games is not accurate in the least bit. Single player games may not be as popular with the kids these days but in no way are Single Player games killed/dead.