At least you know when the movie takes place in the saga.
But if you don't understand why the team on Scarif were all written in the script to die, then I can't help you.
Again, I say it was pretty obvious that they would all die because you never hear of them or see them ever again in any of the sequels. The fact that Episode IV takes place almost immediately after Rogue One is further proof.
Did you also watch the movie Titanic thinking perhaps there was a chance it would not sink?
Naah your point still doesn't stand. Just cause you don't hear of them doesn't mean anything.