It depends.
I wish a leak from Retro Studios, since they're never ready to talk.
The project beast leak thread which started with a few potato screens and exploded with the leaked gifs is still up there as one of the best threads on gaf. Hype, denial, Pixel experts. It really had it all.
Part 1: Couple hundred pages but worth it. (old GAF threads)
Part 2: Then the gifs hit and hype exploded.
TLoU 2 definitely wasn't expected to be announced there or so soon after Uncharted 4. Shinobi did very vaguely hint it would before the event though, but everyone missed it. Why I really don't mind early announcements, that are done well, you just beat the leakers to the punch and in the obviously gonna happen cases, the devs haven't got to pretend it's not what they are working on..1. I just cannot relate to this at all. it's a commercial. there's no sanctity here. I'm not saying i like, WANT leaks or whatever, but if they happen so be it
2. iirc it was pretty much known ahead of time that TLOU2 would be announced, and that didn't stop these folks from getting excited
i'm not trying to dump on people for liking things or being excited about upcoming games--i get excited about games all the time. but the theater and spectacle of advertising is utterly meaningless in the grand scheme of things. i'm interested in the game, not the commercials
Sometimes, there are "leaks" too, you know. It's a thing in current marketing strategies.