To be honest, when I'm asked to summarise, e.g. in meetings, I struggle immensely because I don't see that you can sum up anything that easily without just providing opinion rather than fact.
"So what's best, X or Y?"
I can give an impartial, fact-based, long answer.
But if you want one or the other it will be opinion unless the answer is blindingly obvious. And your opinion may differ.
The thing is that the simple answer is fact, not opinion, as well. If someone wants a short answer and only a short answer, then they are implicitly trusting that you are aware of the detailed facts and are trusting you to make the decision for them. And that you can back up that decision if needed. Sometimes they will disagree with you and that's when the why? comes next, but if they agree with you, a lot of time has been saved not going over the details.
As to trusting opinions, if I've been working with you for a while, I am already aware of your knowledge and understanding and have decided to trust you if the question falls into the scope of awareness. Unless proven otherwise, your knowledge has been proved to me already and I don't need to be convinced any further.
It's an odd thing in human communication, and those people that are on the autistic spectrum can find it hard to understand, but most people are good at working with summaries and partial knowledge updates. If fact A, B and D haven't changed, then you only need the changes to C to catch up to the current state.
Think of it like a diff patch rather than getting the whole source file again when you already have most of it.
Take it this way in future, if they only want a yes/no answer and they accept it from you, they TRUST you and RESPECT your decision and knowledge. It's a good thing.