I think the case is not that people knowing Scala are unable to see the problems of the language (e. g. scala.Enumeration).
The thing is that people knowing the language can easily tell apart people who never seriously tried using the language from those who did, because the complains of the first group are so much different from the other group.
The thing is that people knowing the language can easily tell apart people who never seriously tried using the language from those who did, because the complains of the first group are so much different from the other group.