Joel dies at the start, and TLOU is still a game, so while spoilers could ruin stories of games, I could see myself buying a game either way even if something gets spoiled. And ppl watching their favourite streamers play a game proves nothing, because they could have already played the game (some people have A LOT of free time), or they simply don't care about the game. I know I wouldnt be upset if my little pony got spoiled for me. And even I myself might watch ending scenes of movies that im interested in, but not enough to watch it properly, like the trap scenes in saw movies because of morbid curiosity.