This is mostly true.

The big thing is the NDA or Non-Disclosure Agreement. The productions have people who watch social media like hawks to stop photos and leaks the moment they happen, but sometimes things slip through. Everyone signs it at the start, and since we all enjoy working and earning a living - no one goes around spoiling big secrets typically.

People do get a bit star struck at times, but it passes quickly as the majority are professionals. Additionally, when you're standing outside in the pouring rain on a night shoot for 15-hours while the talent has to do 20 takes due to forgetting their lines and you are dead inside, the grandiosity of it all tends to diminish.

Plot points are the bigger leak that studios have to worry about, and while scripts are sent out (I get these for example), it is typically on a very need to read basis.