This is not a matter of semantics, if you ever want to understand relativity the FIRST thing you need to do is get rid of the concept of absolute motion. As long as you think in those terms you will never be able to understand it.

And addressing something in a followup is no good - fix your initial post to be correct in the first place. Reddit allows you to edit your post.

If she had started by explaining relativity her post would have been twice the size and she would have lost half the audience. Doesn't it matter to you that people were actually interested in the topic and participative?

And why is a follow up no good? She didn't follow up to fix anything. She followed up to follow up. (And mentioned it by, yes, editing her article).

The problem here is that when explaining things improperly to be "good enough" you have to be very very careful to make it clear what you're doing.

In my opinion, she failed to properly do that and crossed the line between "helpfully simplifying" and "incorrect".

I went through your comments and you mentioned that "in a nutshell" the fact that there's no such thing as a full stop in space is why "this explanation is actually doing a disservice". But that's confusing to me because she clearly stated - relatively to motion - "Those things are true, but we're ignoring that kind of stuff right now."

Can you point out exactly where she crossed the line in your opinion?

The confusion being expressed among commenters here is what I'm basing my assertion off of. Simplification is fine, but I think in this case it pretty clearly set a lot of people down the wrong track.

Some confusion is to be expected. After all, a lot of the concepts are pretty tough to comprehend cleanly.

The important part of relativity is that there is no absolute reference frame, all motion is relative, thus the name. The mathematics behind time dilation is an aspect of that. Teaching someone about time dilation without teaching about the fundamental nature of relativity is a disservice, in my opinion.