I'm the blog author, Rich Archbold from Intercom. Just to clarify …
I wrote this blog, with the exaggerated / cliched title, to try to speak to the large cohort of over-confident, under-skilled and often lacking-enough-self-awareness, managers out there. I was (and often still am) a member of this cohort. Being a great manager all the time is really hard and almost impossible IMHO.
The goal was to hopefully try and generate some more self-awareness and introspection and thus make life a little fairer, more pleasant, more growth-oriented and hopefully more successful for all concerned.
I wasn't trying to deny or downplay that people also leave their jobs for all of the other reasons highlighted by folks here.
Thanks, Rich.