Here's the thing... We're two/three weeks from release. The fans already know what's coming, and everyone else doesn't care.
The AP newsletter was approved by Marketing before distribution, and Marketing is actually the ones responsible for scheduling announcement.
The billboard was per luck, and isn't a huge deal because (again) we're less than a month from reveal.
The yearly leaks are the cost of doing business. When third parties are brought in to market, you contract an embargo and cross your fingers no one breaks it. The Evil Dead leak was the biggest in recent memory, and that was something the parks had no positive control over.