[desu_]

Ad hominem is wrong, but so is argument from authority.

My professional opinion as a blockchain researcher I’ve spent the last 15 months researching the implications and possibilities of blockchains and related “distributed trust technologies” from a business and societal point of view.

And dirtyaura's comment consolidates the author is some figure we can trust mantra.

In the end, the article states that people should not put their savings into coins but smart contracts are nice. Something others have said before but it's more clickbaity to state that it's coming from a professional blockchain researcher.

[ChrisLomont]

Claiming it's an argument from authority is the fallacy fallacy.

An argument from authority goes: "I am an authority therefore the following is correct." This is nowhere near that.

He correctly stated it was his professional opinion that..... He didn't claim the argument is correct because he's a professional. And he is a professional, doing this work in a professional context for 15 months.

So it is absolutely correct to state "my professional opinion is...". He has likely put far more work into this, and certainly with better background and training, than probably anyone on this thread questioning his credentials instead of addressing his message.

[desu_]

It's not a fallacy fallacy since I point out one weakness in the article but do not assume the proposition is wrong for that reason. Actually, if you read my last paragraph, it's obvious that I even agree with the author's argument to some extent. I only attack him for making a boring claim more clickbaity through his credentials.

From my quick skimming, mostly apo questioned the credentials. Yes, you are using ad hominem against the one you accused (rightly of doing so).