Hiring Ethics of a Fringe Tech Stack?

The small startup where I now lead engineering is planning more engineering hiring, as well as picking stack for some major new development. And our stack might be a key factor in being able to hire high-powered people -- despite not having FAANG money and prestige, and despite no unicorn strategy lottery ticket.

One of our stack options, to be nimble, and to be very attractive to hiring candidates, is to use one of those tools that's not popular, yet is beloved disproportionately by engineering-as-a-passion developers. I'm thinking, in languages for example, things like CL, Scheme, Haskell, OCaml, Smalltalk, Erlang (though that's more popular), etc.

The biggest question on my mind at the moment is -- given the current industry emphasis on always keeping the latest most popular stack buzzwords on one's resume -- the ethics of hiring people to put a few years of a fringe stack on their resume. Would it be doing the hires a disservice, in a way that recent grad developers might not realize?

In addition the fact that they probably won't be able to get a job with that stack if they move, there also seems to be a lot of sterotyping and stigmatizing in hiring interviews right now. Like one article of clothing in an otherwise fashionable wardrobe, at a mean-kids school, is, "like, so 2019, loser."

Though I think an aspiration to provide potentially lifetime great working situation and career opportunity to everyone is a helpful guide, we shouldn't plan that we'll be able to do that forever, for everyone. And the norm is for developers to move every couple/few years, so we should also be guided by that reality, and how we can be good for people's careers if they do move in a few/several years.

Summary: Can we attract some of the best developers using the fringe tools they really want to use, without doing them a disservice? I hope the answer is yes, and want to pick HN's brains on this.