Long story short from a business perspective - good luck logistically scaling a dev team from 2 founders to 100 devs as quickly as your app does. Elixir devs are hard to find and are expensive.
Having said that, a single team of seasoned Elixir devs can achieve more/better things than 100 average devs using the usual SPA/API/microservices-JS hell with all that modern unneccessary complexity. Saying this as a former DevOps guy babysitting the mess of multiple of these teams before.
Another good thing about Elixir is that the odds of you actually needing 100 devs coding in it are close to zero. I've been in financial EU startups that moved tens of millions a month (they were not huge) with the grand total of 4 devs. The only problem was clearing up customer requirements (i.e. our product people dropped the ball and left us doing most of their work).
And expensive? Yeah but I wouldn't be against that if I was an informed business owner. Most Elixir devs are refugees from other tech stacks and are quite senior. Good talent should be compensated well.
Having worked at multiple unicorn+ SaaS products, the product feature demands are significant.
Yes if you have one sole feature that you can pour all your engineering resources into like whatsapp delivering messages then it makes sense you might get away with 2 Elixir devs.
If you are working at a unicorn who just raised $250m in founding and now has to deliver 100 new features this year... well the elegance of the language won't help as much as you think.
I'll take quality of life over money any day, but I realize I'm in an extremely small minority.
You'll never need 100 devs to work on a single elixir project. I as a solo dev built out the backend for my startup to profitable. We keep discussing bringing on a new developer during the occasional crunch but its been 5 years of operation and we haven't really needed it aside from increasing the bus factor. features go out fast enough as is. elixir is very productive.
based on my experience, if you need more than 5 developers, you should separate out features to independent systems and have them communicate with each other over established interfaces. Then you can use the language specialized to the task at hand. Either way, 100 engineers on a single codebase is not going to be efficient no matter what language you are working in.
That said, this article is about startup. the name of the game is to crank out features and aquire users. elixir is performant enough that you're not blowing your budget on cloud infrastructure and high level enough that you can build out and maintain your mvp with a skeleton crew.
If you run into a situation where you suddenly need to scale to 100 engineers, thats a great problem. it means you have revenue.
I don't think devs and talents are too hard to find, if you are willing to look and be flexible.
you just have to post where they are. i strongly recommend the newsletters, the jobs channel on the elixir slack, and elixirforums. all great resources.
We've had non senior people onboarded a few months and they are doing well with Elixir at the moment, fwiw!