These theories are all nice and relevant, but ‘happiness’ is the word real people use.
Look at the headlines of the posts you shared. It’s in there. I’ll gladly use this term as an umbrella for all these things if it helps people get the message.
So while I agree with you — there’s a lot more to it — I’m oversimplifying too to make a point. Just like the folks you mentioned. Except I’m not nearly as important as they are :)