Writing for others poses difficulty because writing is linear, and thoughts are not.
Think of a valley shaped like a bowl. Mountains jut out from all sides and in the center lies a traveler, your reader.
You have traveled to many peaks that surround the valley. You've seen the many perspectives and angles that make up the valley. As well-traveled valley dwellers, we forget that some people are new to the region. When we meet them we talk to them as if they are natives.
In real life, we don't talk to foreigners as if they know everything about our geography. As writers, we treat our readers as if they do.
We're in a constant battle of trying to understand what our readers already know and what they need to know. Being a writer means turning each of your journeys into a path that is traversable.
Talking too much about tangents leaves readers confused about where you're headed.
This is the battle between clarity and complexity. Meaning gets diluted the farther away from the source the information goes.
Like the telephone game, transferring knowledge can get lost in the translation process. So, I should write as if I'm the source, and people will treat me as the source.
Identify as it and act like it. People will begin to treat you like it.
Most writers solve this by simplifying everything. Some writers take this too far though. Avoid leaving out interesting details in pursuance of simplicity. Instead, pursue order in the chaos.
Writing is taking complex information and diluting it into a cup that isn't so bitter. As a reader reads, the more complex the writing is, the more bitter it tastes. Some readers may sniff the cup and realize it's too strong a mix for them. Others may sip a bit and not like the aftertaste.
Writing should be sweet. Write a cup of hot chocolate. Throw some marshmallows in there.