I see it differently. If you are writing documentation for a system you know a lot about, things are completely simple for you right then right there. But as we all know in 6 months you'll look at your own code and think "who the ... wrote this?".

So avoiding the word "simple" isn't about accommodating the 5% of your least intelligent users and dumbing down the content, but the > 90% who are not so into the topic as you are right now.