Could you cite an example of how Scala is unsuitable for the web? Between Scala and JavaScript, I would pick Scala in a heartbeat for one reason alone - it's strongly typed. Both of them offer OO & FP.
Strongly typed was one of the problem I found. TypeScript offers a better alternative to typing on the web because it keeps the compatibility with javascript and also have a real any type when it's really necessary. Typescript now can import raw js without types definitions unlike Scala.
I believe Scala can use javascript libraries either dynamically or with type definitions in exactly the same way as TypeScript?
I tried to use TypeScript but the type system just wasn't good enough; when you've been working in a strongly-typed language like Scala for a while, a language without nominal types or HKT just isn't going to cut it.