One point that the author fails to mention regarding Jetbrains is that they developed Kotlin and that Intellij at this point is largely implemented in it. Their whole strategy features a lot of Kotlin at this point. So, the best IDE for Java is built by the company that develops a drop in replacement for it. Not a minor point to make. The IDE that Oracle acquired along with Sun (Netbeans) is still there of course but it's rare that I meet someone who even knows what that is.

This is actually also a weakness because there is no good competition in terms of alternative Kotlin IDEs. Eclipse and VS Code have Kotlin plugins but they are nowhere near as good as their Java support. Nice in a pinch if you really can't be bothered to install Intellij.

Java undeniably has great alternative IDEs. I think it's still unrivaled in the wide variety of very decent IDEs and by pretty much every other language. And that has been the case for a long time. Eclipse and Netbeans are still around and both still do a fine job. If you use emacs or vi, there are decent plugins for those as well. VS Code of course has pretty decent support. Kotlin support for all of those is not at the same level.

But one positive thing that has come out of Kotlin (and Scala) keeping the pressure on Oracle is that they have rapidly rolled out a lot of new Java and JVM features in the last few years. JDK 17 is a nice piece of technology with lots of under the hood changes that benefit all JVM languages. So is Graal. I think the efforts to make Java more usable are also going to be nice for people with Java code bases.

Like the author though, Kotlin is my main language at this point.