I think the main problem with this article is that its authors are living in a bubble. As such, they think they can speak for the popularity of Angular 2, when really the kind of people who will use Angular 2 couldn't care less what they think.
The authors fall in to the subset of all JS programmers who live in the React ecosystem AND are in to stuff like pure functions and Elm. To be fair, that subset is growing (in part because it has a high density of "thought leaders"), and I think they make a good argument why programmers in the same subset will avoid Angular 2.
But here's what they forget: that subset is a small *minority* of the overall community. Take the recent (2016) Stack Overflow developer survey. 62,588 Javascript programmers answered it, and here's the popularity breakdown of front-end stacks:
AngularJS, JavaScript, Node.js 16.6%
JavaScript, PHP, WordPress 16.5%
JavaScript, PHP, SQL 14.3%
AngularJS, JavaScript, PHP 11.4%
JavaScript, Node.js, PHP 10.2%
JavaScript, Node.js, React 9.7%
AngularJS, JavaScript, SQL 8.0%
That's right, React users were less than 10% of the total, while Angular users were 36%.
So yeah, the functional-loving subset of the less than 10% of developers who use React will probably eschew Angular 2. In other news, Linux programmers are unlikely to develop for Windows and it's unlikely to rain on a sunny day.
But does any of this have any relevance on Angular 2's popularity? I wouldn't bet on it.