Counterpoint counterpoint: Esoteric languages attract PL nerds, who are much more interested in using every new/different "expressive" feature of the language than in getting business done using clear code understandable by anyone on almost any level.
True. But if you have a good well-enforced, sane style guide, then expressive powerful languages can be a good thing. If you hire devs who care more about playing with the language than delivering value then you're hiring the wrong people. You can't ditch these languages because some people are sometimes attracted to them for the wrong reasons.
I actually did start a company using Clojure. All these points are true. Yes, it helped filter candidates in the early days, and also helped attract people to jobs that might otherwise not be that interesting or competitive. It's difficult for pre-funded companies to compete with the FANG companies.
However, there were negatives. At the time the Clojure library landscape was less mature. Clojure developers would also tend to abandon projects to create "the next best version" which made migrating and keeping up with the libraries of the day difficult. Most of the libraries were very rough around the edges too. On the other hand we could use any Java library which was a boon.
As the team grew, it became harder and harder to hire people in larger numbers. Especially in a single timezone. Also it became apparent that many of the people who were very happy in the early days, were increasingly less happy as we added standardization and protocol to our dev process. As some commenters pointed out many of the people attracted to Clojure liked playing with the latest and greatest, and things were "boring" when they couldn't work with whatever the latest fast changing trend in the community was. Trying to teach people Clojure also an issue. For some it was challenging, and for others, they were not really interested in using it.
It was a good learning experience, but I don't think I'd do it again. There is something to be said for using "boring" technology for the majority of your tech stack.
I must note switching from novelty to boring phase is a crisis which every growing project will come through once it starts to expand its workforce. I saw it in teams with very average tech stack many times.
Esoteric languages by-nature have smaller populations of devs. They demand higher salaries for their specialist work. This can hurt you as you scale - salaries continue to increase (secularly), and the pool of possible engineers begins to shrink within your locale.
If you hire developers based on the languages they know / think of languages and stacks as part of the long-term identity of a developer, then you should not use esoteric ones. This is well known! On the other hand significant parts of the industry don’t do the former, so they are free to do the latter.
As an example, nobody knows Go when we hire them to write it.
Hopefully WFH helps there. In my niche Scala it does. We can hire more broadly. We also hire ppl with an aptitude for Scala and keep our style simple. That helps.
