This goes against everything I've been taught by framers...
I'll refer you to the paperwork you are given by the manufacturers on how to properly install their trusses, when you buy them. It's all in there.
The framers who taught you, either choose not to read that paperwork, or they choose to disregard it.
If you follow the proper published procedures, (including installing the drywall properly, ..that's a whole nother issue), it all works just fine.
Many builders are okay with not doing a lot of things by the book, when they didn't have to.
That's the entire reason for building codes.
There was a Roman emperor who got tired of builders building shoddy buildings that were collapsing, and killing the families inside. He decreed, that any builder who's work fails, causing death, would himself be put to death.
I bet it had an immediate affect on the quality of construction.