I feel like it's in the best interest of the employer to leave the choice of tools fairly open and see what the potential employee elects to use. For the example given in the article (a basic web application), I'd be very interested in whether the interviewee decides to go with a heavy stack, does it completely in vanilla JS, or something in-between.
I wonder about this. I'm pretty new to js frameworks and I see the advantage when things need to scale or get very complex, and I get that companies use these things. But for a simple assignment like this, is it better to use vanilla js and maybe handlebars, or "show off" that you can implement all the routes and whatnot in Angular, even though that's overkill? Or maybe the interviewee's justification of their choice teaches you that they understand the trade offs.