I have the same problem.
I took to highlighting emails for "Short version" and "Long version". The only people who bother with the long version are the people with an axe-to-grind with what the email is about, people who are similarly autistic-like (yeah, I'm definitely on there somewhere too), and those with an interest in the actual fine details of that particular area.
But I work in schools so I can tell you now that, however hypocritical, the entirety of education is set up as "lies to children", in fact "lies of decreasing magnitude". At first atoms are the smallest thing. Then electrons. Then quarks. Then strings or whatever. We do it to ease them in, and allow them to understand at whatever macroscopic scale is necessary at that time.
I'm not sure it's an entirely bad method, but the phrase "You'll see later / when you get older that this isn't exactly true" doesn't HURT anyone to say and we rarely say it.
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 problem I get is that when opinion differs, the next question is always "Why" and despite lots of reasoning from an expert hired for exactly that purpose, there's often no convincing someone anyway.
But, as this post probably shows, I find that the REASONING for an answer is often more important than the answer itself. It tells you how much people have thought about it, how long they've been working with such things, how detailed their knowledge is, and that - ultimately - tells you whether you should be trusting their opinion against others.
I get told off for overly-long emails and posts all the time, and yet I often hold back much more than people know.
(Pity the poor guy who tried to argue Data Protection legislation with me and got a written-up explanation, with citations, all my own wording, from memory, in under an hour that took him a day to read).