The author's premise is that you burnout because you do not spend time on the things that truly fulfill you, whatever those may be. It is very possible, and maybe even probable, that people who do not "work so hard" can still experience burn out because they do not use their free time to do the things that fulfill them.
If you are working so hard that you simply cannot find any time to fit in fulfilling activities, then yes, you should not work so hard.
If you are being taken advantage of and pressured into working too hard without adequate compensation, then you should find a better job.
However, "not work so hard" is not an answer to the problem as outlined by the author and seems more like a response to the headline than to the article itself.