I really like Sasha Chapin. He's a writer, and also a writing coach. Since I like him, he comes to mind when I need an example to illustrate a common mistake.
Words are defined by other words, so it's easy to get mixed up in them. One of those words is simple.
Sasha writes about Paul Graham's writing. Paul is a legendary Silicon Valley investor, but he's also a great writer.
Sasha struggles trying to praise a quality of Paul's writing. It's simple, but not simple in these little ways here and there.
The common error lies in the definition of simple: it's the opposite of complicated, not complex. Something can be simple and complex at the same time.
In watchmaking, any part except the hour and minute hand is called a "complication". Day, date, phase of the moon, it makes the watch more complicated than it needs to be in order to tell time.
This doesn't mean a watch mechanism that only tells hour and minute is simple. Simple just means reduced to a state of minimum complexity.
And no less. Reducing complexity beyond the minumum is oversimplification. Like pixellating a picture or compressing audio, it changes meaning. A quartz watch seems simpler than a mechanical; unless you're an astronaut, where exposure to electromagnetism renders a quartz unreliable.
The technical name for watchmaking is "horology". Sometimes technical jargon speeds up writing if you're talking to a specific audience. But too often it can be a signal the write r wants to send about how smart they are. Same with writerly flourishes.
Write about something that matters in plain language. That's hella hard already.
Simple ain't easy.