For a while I've been thinking about people that tout themselves as experts in X but are really (self-professed) experts in being expert at X.
I'll call these types of people the Meta Experts.
One example are the "professional bloggers" whose own blogs are actually just about how to be a professional blogger.
It's hard to say if their advice is useful for professionally blogging about X because all they themselves professionally blog about is professional blogging.
A classic one are the people that tell you how to get rich in, say, real-estate who actually make more of their money, not from real-estate, but telling people how to make money in real-estate.
A lot of "how we do growth hacking" or "most important metrics for your SaaS startup" type posts are from founders of companies that build tools for growth hacking or for doing SaaS metrics.
There's nothing wrong per se with this type of content marketing. But they always run the risk that how you track metrics for your metric tracking tool SaaS company isn't the same as how you track metrics for any other kind of SaaS company.
Most recently I've noticed how many self-professed multi-passionate / multipotentialites are focused on businesses around career counseling, etc for multi-passionate / multipotentialites.
Deciding that your focus on life is helping multipotentialites is great but it's not really being a multipotentialite yourself.
Meta Experts may be too kind a term. In many instances of this kind of activity, there is more bullshit involved than "Meta Experts" would suggest.
I think sometimes it's legitimate which is why I chose a neutral term :-)
I think it's important to distinguish the meta expert from someone who is just better at teaching X than doing X.
For example, there are world-class sports coaches who aren't world-class at the sport they coach.
That's not who I have in mind with the term Meta Expert.
Perhaps even my real-estate example isn't a great one. The "problogger" is perhaps the best example because technically they are blogging professionally but they just blog about blogging. Hence the "meta".