That's not how it works. Enter the CTF and you get supplied as a lead to companies as a potential hire for doing well (if you want), it's not that you use it as a competency canary on your CV.
That's my point. I'm being supplied as a lead for investing time learning something that I will not be able to use in any potential position. Why should I do it? I'm genuinely interested in understanding this because it might blow up and I'll have to learn it anyway.
In addition to the "it's fun" thing mentioned by other commenters: I always learn gobs of transferrable stuff when I do things like this. Just solving different problems with languages and tools I already know usually teaches me a ton of stuff, let alone using it as an opportunity to try out new things in a low-risk environment. Take the difficult, data heavy, level 6 described in the article: maybe you can solve it using formulas you already know how to write, but maybe instead, it's a good chance to deploy a real Hadoop instance for the first time and see if you can get that to work, or maybe you want to learn Julia, or make a really optimized version in C++14 or Rust. I find these sorts of "programming exercise" things to be great learning experiences, regardless of the level of artifice.
My understanding from reading past posts is that they think this could be a great way to discover people who would be interested in roles at companies they hadn't previously considered. Shotgunning everyone who plays as leads isn't a great model as it lowers perceived quality of the candidates they send on ("I got a lead for this amazing developer, but she didn't want to change jobs at all, wtf?!").
Think of it as a game with "new job" as a piece of available loot. Play it because it seems fun (and you still might learn something that you can use later).
