NeoGAF actually has instructions for spoiler etiquette, and the age of the game isn't mentioned at all. It says that users are expected to use spoiler tags everywhere except threads "specfiically marked as post-game discussion" and "threads about the sequels to existing games." Now, obviously Final Fantasy 7 is technically a sequel, but I think we can agree that the spirit of the guideline here refers to series with a continuous story. As the FAQ says, you shouldn't be reading about the second one if you haven't played the first one; that
is your fault.
Unless you completely eschew games from older generations, there are undoubtedly countless old games you haven't played and would not want spoiled for you. New people are born every day, and classic games find new players every generation. Right now there's
a thread in OT about Lolita by Vladimir Nabokov, a book that's almost sixty years old, and it's full of black bars. FF7's Steam release will introduce the game to innumerable gamers who either hadn't gotten around to playing it or were too young to play it when it came out. Why spoil the game for them when it's so easy to avoid? The game's age and your own laziness are not reasons with which I sympathize.