What do you mean?
I'm into Effect from long time and it really scales well the more complex your applications.
Schema is way more advanced than Zod by the way, both at type level and functionality it has a proper decoder/encoder architecture.
You can encode "this isn't just a string -> non-empty-string -> valid email pattern" but a confirmed email the user has clicked on at the type level, by leveraging effectful schemas (and durable workflows if you want).
You may not need it 99% of the time, I myself rarely use that, but it's not a fair comparison.
Zod is more ergonomic, has easier apis and is perfect for most users. Would not recommend schema unless one buys the whole package.
In all fairness it does require buy-in and gradual adoption isn’t perfectly seamless or frictionless, but I think it’s worth it. They’ve done an outstanding job with it.
Which functional language has a similarly huge ecosystem, works across the frontend/backend, has first class support of different runtimes, provides similar ergonomics, has meetups and conferences in so many countries and is easy to hire for (all you need is solid TypeScript)?
There's a reason effect-ts keeps spreading despite its syntax and learning curve, and I say it as somebody that used Haskell, functional Scala, Purescript, Elm, Racket, Elixir and tested another half a dozen.
Give me an Elixir with properly powerful types (not gleam) and I'm in.
I'd gladly throw effect and typescript especially out of my work day, but I see no sane replacement at complexity scaling.
I wouldn't personally recommend effect without a solid champion in the team and without having the complexity needs for it (I'm talking recurring durable worklows, complex encodings, suspension, retries, etc) and even if you have them the price is steep without a champion, but that's my 2 cents.
You use it for an agentic cli (opencode uses it e.g.) not a simple crud (which is 90% of web dev industry).