I keep an eye on atom-editor daily. I noticed a while ago that it is very common for atom to be misused as a tag on these questions. The atom tag is for the Atom XML syndication format, where atom-editor is for Github's Atom text editor.
This triggered my tagging OCD and a few weeks back, I went through the entire history of atom and read every question, looking for atom-editor questions. I didn't keep count, but I am pretty sure I retagged several dozen of them.
Since then, I watch both tags daily, and several times a week I retag from atom to atom-editor (and some questions simply add both). The atom tag excerpt already has a notice to use atom-editor, but clearly people are not following the advice consistently.
I submit that atom has become ambiguous, and might be better renamed to something more clear. My suggestions would be atom-xml or atom-format. And it would only make sense to then burninate atom.
EDIT: I like JeffreyBosboom's suggestion better than mine - atom-feed.