Technical writer here. I avoid saying something is "simple," because whether it's simple is subjective and is relative to the reader's background knowledge. So at best it's unhelpful, and at worst it can be insulting.
If you're stuck on a task, the last thing you want to hear is that it's really simple.
On the other hand, I would write that X is a simpler approach than Y, if I was comparing two possible approaches.
It's not a good feeling when you find something "simple" to be hard. Few tasks are easy when you're a new programmer still wrapping your head around conditionals.
If my docs might be used by a new programmer I try to avoid alienating my users with the word simple.
When we say "simple", we use it as a way to say "not complex". If we want to say "not hard", we say "easy".
Words should be used carefully or we end up with no word to say what we mean. That's why there's literally no word meaning what we want to say by "literally".
But from context you can determine whether "literally" means "literally" or "figuratively". It's the same with "simple", you should assume it means "simple" and not "easy" in the case of a documentation where words are chosen carefully.
If you're stuck on a task, the last thing you want to hear is that it's really simple.
On the other hand, I would write that X is a simpler approach than Y, if I was comparing two possible approaches.