Not everything scales horizontally. Your database for instance is going to be scaled vertically to its max long before you think about using federated write servers. Sure you can use planetscale but that comes with its own considerations and tradeoffs.
Also, higher performance translates to lower machine costs. Our server costs would easily be 4x if we ran rails. given that elixir is 80-90% as productive for writing code in the short term, its a fair deal. Over the long term, we've found elixir to be more maintainable since there's very little magic and the immutable data structures and lack of magic make it super easy to debug.
Thanks to the performance of our system, we've also managed to get by without setting up caching. (we'll probably need it eventually but our performance gains have come mostly though fine tuning our sql queries. Ecto gives us way better control over the output sql than active record or sequalize)
Also, higher performance translates to lower machine costs. Our server costs would easily be 4x if we ran rails. given that elixir is 80-90% as productive for writing code in the short term, its a fair deal. Over the long term, we've found elixir to be more maintainable since there's very little magic and the immutable data structures and lack of magic make it super easy to debug.
Thanks to the performance of our system, we've also managed to get by without setting up caching. (we'll probably need it eventually but our performance gains have come mostly though fine tuning our sql queries. Ecto gives us way better control over the output sql than active record or sequalize)