The original post had it as part of the title, with no spoiler warning. The mods changed it to what it is now. I can see why it would seem like an oddly vehement reaction with the current version, ha ha
Even with the old version, leaked announcements never get spoiler warnings on here. Rage 2, Pokémon let's go... Leaks are put on here all the time.
Because these kinds of leaks are very different. Firstly, because leaks such as Pokémon Let's Go usually come with a lot of doubt over whether they're actually real, and also because even if they are, people can usually speculate for a while about what this leaked game really is like, and such.
With this, though? We know it's real, for sure, and we know it'll be announced today - probably as the Direct's final announcement, which makes it even worse - and there's no suspense, either. We know what it is, and what it'll be like. It's Simon Belmont in Smash. Sure, we might not know the exact moveset or whatever, but I think everyone can sort of tell what it'll be like.