I would second his opinions and take it a step further ... people here will debate tech stacks til the end of time but in the grand scheme of things picking a tech that has a much smaller and more expensive talent pool could be a scenario where that choice is a death knell for the project (could be, not will be). The low adoption rate also means more abandoned libraries, less variety of libraries and possibly having to DIY things. These all add time to a project on top of a learning curve (which will vary per person) which make it more expensive.

I'm not advocating always pick something with the lowest $/hour rate. There are a lot of other choices out there that are not going to have risks around technology choice.

Long term maintenance is a concern too, not of Elixir, of the apps built with it. When that app goes into a maintenance mode (still providing value just doesn't need new/active development) the devs will likely move on to other work/companies. Now to do support work you have a small+expensive talent pool that doesn't likely want to do support work.

If you're a fan of Elixir, don't take this as me saying "no", I really like the things I learned (and continue to learn) working with it. Its just trade-offs that mostly are on managements shoulders. The developers advocating for it take no risks really.