Giving my own two cents on this but you do realize that people not wanting to go into the game blind does not necessarily equal that they want to know everything about the game, right? You try to argue that people following official news don't care about spoilers, but what all is revealed is significantly less content than the stuff that gets leaked given leaks usually cover almost the whole dex. There is no need to treat "person who wants to know absolutely nothing" and "person who wants to know everything possible" as the only existing options as if there is no middle ground. I've personally been in touch with the leaks and one of my main takeaways from it is that people who are going in blind are going to have a blast with some of the ideas they are pulling off just out of how unexpected some stuff is. Trailers handpick information so that there is still surprises left to be had in the game aa opposed to leaks giving you direct info about everything.
The point about "no one else can have nice things" is weird to me because discussing leaks also ruins the fun for people who want to go into the game without knowing leaks. By all means discussing leaks here would also result in some people not having nice things, so this point is completely irrelevant. Also i'm sorry but I genuinely cannot take a "back in my day / these darn kids" argument seriously in this context lol, tech has grown a lot in the past decade so obviously not only there are more things getting leaked but they also more easily spread. And in any case its not like talk like this never happens on Smogon, its just usually reserved for when the game is actually being datamined because its easier to comment on mons when you know for sure their stats/moves/abilitites than when you only know their name (and for most of the leaked mons, not even that, just vague descriptions of their designs)
I honestly feel like the best way out would to be having a specific thread for leaks and keep talk about it there, but I ain't this subforums mod so I can't comment on how efficient or useful that would even be. I just personally think its nicer to give people who want to avoid leaks a place where they can discuss the game safely given leak talk is absolutely everywhere and if people want to discuss leaks they can pretty much find other places to do so very easily