I believe that this entire blog post is comparable to asking for a definition of car that includes helicopter but excludes jet: utter nonsense. All 3 are vehicles and none of them are the same.

I move that bean bags are neither chairs nor stools, but rather are within the same category. All 3 are seats. A chair has a back while a stool does not. Others have noted this same point. A quick check of wiktionary.org confirms that this is correct.

If bloggers spent more time thinking and reading prior to writing then fewer people would waste time reading nonsense of the attitude "I have a misinformed opinion, therefore you should listen to me."