The title reflects poorly on the article. It’s not really a case against Kotlin, rather a reminder that there are tradeoffs to be made when adopting a new technology.
And I agree that it is usually valuable to take the time to understand how introducing a new language will impact your current project and your team.
The interesting thing about this sort of article is that, while there’s a lot of truth to these issues, the fact that significant companies are starting to complain about them says that Kotlin is starting to get into mainstream usage, and hitting the growing pains associated with that. It’s an interesting language, and I hope Google and Jetbrains are invested enough to take it where it has the potential to go.