From one point you're right. If someone right now posted an actual leaked footage or art from MK11 on some random Reddit post it would blow up in less than 2 days and everyone would be talking about it. BUT, presentation also matters.
A hyped up, properly done announcement trailer will do you way more good, than a trailer which will be seen by a limited number of people. Trailers aren't only for us, who know MK franchise, but also for those who never saw or heard of MK.
And for that reason a proper presentation needs to be done.
As for those Youtubers. It's like that guy MrBossFTW. Keeps talking about same thing for a week. Or starts making up bullshit predictions, just to have something to talk about.
There are only two things I trust. Official reveal or Reddit leaks (the last one, is shaky, but has a decent ratio, when it comes to being true.)
I agree that something which gets teased and then later released will likely have a bigger impact, like the Bethesda Fallout teasing that they've currently been doing.
As for trailers, I also agree that they are for both types, but in this day of "leaks" a trailer at an event like Combo Breaker could also build up hype, like how Combo Breaker essentially went nuts when the TMNT were announced for Injustice 2.
While people knew about Enchantress and Atom, not many were likely thinking all 4 of the Turtles would be announced.
So on 1 hand, yes the reveal was said to happen there so people were expecting something, but on the other hand, and event like Combo Breaker for NRS to reveal a trailer for something isn't out of the question.
The Injustice 2 TMNT reveal is likely why people thought that we could have gotten something at Combo Breaker, because that's where the last big character reveal for a NRS game was at, and NRS tends to have a pattern, as even spoken / joked about by Ed himself at the Brazil Game Show.
The YouTubers have gotten to the point where I stopped believing anything that they have to say, a long time ago
(around the time of the release of MKXL, when they kept on dragging the topic of KP3).
I don't even trust the MK reddit anymore as it has essentially turned into
"my brother's, friend's cousin knows someone that worked there, and this is what they saw."
And, while some of that could turn out to be true, I remember a lot of that
"I know someone who works there" crap going on with MK9 and MKX in 2010 and 2014, respectively, which never turned out to be true.
Not to mention, the MK reddit has also turned into
"If ___________ isn't in this game, then I'm not buying it," which reminds me of a lot of the horseshit that went around on this site during the time of MKX, with people calling others names for not wanting certain characters in and essentially a
"fvck you for having a different opinion than mine" type of attitude.
It's deja vu.