I've worked with perhaps half a dozen real "language enthusiasts" in my time. People who spend lots of time obsessing over "perfect" language design and non-mainstream languages. People who never stick to a language for more than a year or three, who insist everyone else accommodate their current fascination with some language, and who leave behind codebases full of code that will be hard to maintain because they are a patchwork of languages. Not caring that the organization then has to take the time both train people in thoselanguages and ensure they have enough people experienced with the language to be able to use a portion of their time to train newbies.
On a few occasions I actually researched their job history and found that these people had a tendency to make a lot of noise, but produce very little of consequence. They'd find jobs at the outskirts of projects where it would be easier to indulge in their interests without clashing with the principals. Most of their code would be gone just months after they left the position.
My advice is that if you care about building stuff, don't hire language enthusiasts.