I want to quickly pick up on this as it seems to have been lost in the remaining discussion. After all, the title suggests we are talking about ways to make Scala more popular and I think eyalroth has a point there. When I talk to people about how amazing Scala is, they usually reply “uh yeah? who uses that language though / what has been built with it”. Before investing energy into learning a language it seems natural and reasonable to consider whether there will be any profits. And I think at this point, scala-lang.org does not do a good job at that. I think that this can be considered suboptimal marketing for any technology, really, as you should always sell the client using a product, not just the product.
I propose adding a section showing company’s success stories as eyalroth mentioned. Further, it should also give an overview of the most prominent scala libraries and the absolutely beautiful APIs that have been designed with it since this is an aspect where scala really shines. Even people who dislike Scala usually have to admit that, when it comes to DLSs, Scala absolutely rules due to its flexible and expressive syntax.