Hmm. Fair point for Rails and Laravel (whereas I think React had a killer app in terms of being able to make SPAs without going crazy) but those are tools that you can pick up for a one-off throwaway project - indeed I suspect most adopters didn't "move" to them so much as start doing projects in them and eventually stop doing projects in other things. Scala was never really competing in that space - I don't think anyone would ever say "let's make our website for the next tradeshow in Play" - it's a "heavy" language that needs an IDE and deep familiarity to get the best out of it (and partly that's also what JVM folks would be expecting). So it needed to play for the big core codebases, and for a while it did (particularly when there was no alternative to Spark).

Could they have made Play an alternative to Rails for one-off throwaway websites? Maybe, but the thing that would have needed to be different wouldn't be pushing Play itself, but rather lighter tooling and making it easier to get from zero to pages being served. Honestly I struggle to see how they could've done it without making the compiler and build tool much faster, and either making the IDEs much more efficient (difficult) or making the language easier without an IDE (difficult, and would risk splitting efforts). And even then, you wouldn't really show the compelling advantage of Scala, which is fearless refactoring in large codebases. I don't know that it could ever have been better than Rails at what Rails does, and also we already have Rails. Whereas even if it eventually "dies", Scala has already pushed Java and Kotlin to be much better than they were.