Ditching
(ditching: max power, stick forward and take it as a man
)
Well every briefing is there for a reason. Not all people are able to read or understand the language written so you would need how many pages due to all languages being included?
Many peolpe also have a better way of learning if they are instructed in visual terms instead of only reading. This is why in classrooms there is a blackboard. And you might know if you are an instructor you were told to use multiple colours when writing on the blackboard.
De-pressurisation
For technical reasons.
If you don't pull the mask you wont get oxygen.
Again with the text and the pages needed...
Evacuation
You never know what exits will be availabe in case of an evacuation so it's not good to say where you should exit if in so and so seat.
During the briefing you are instructed on numbers of exits and their location and that it is your responsability to locate your nearest exit and that it might be behind you.
Pax will get on their hands and feet by instinct cause they want to survive in case of smoke in cabin. If one were to brief on every single thing possible in the unlikely event of this or that they would have to meet in 2 hours prior to flight due to technical briefings.
Card vs Briefing
Same reason again
Why
There are still pax that fly for the first time or there may be people who only do it once every year.
They don't not know the instructions as well as a frequent flyer.
And why not just give the briefing there is normally enough time for it.