It's popular for the same reason C++ and JS are popular, hype trains and lock-in. There's no good reason to use it in a new project, people saying "Performance" and "Tooling" need to take a good long fresh look at the language landscape, we're not in 2005.
A trivially easy replacement would be Kotlin, it compiles to the same VM (and additionally webassembly), it is designed and implemented by one of the leading IDE vendors, it can trivially call and be called from Java, it has tons of zero-cost syntactic sugar that covers the inhumane verbosity that Java buries you under till your eyes bleed and your hands scream. A well-designed language, what should have been all along.
A trivially easy replacement would be Kotlin, it compiles to the same VM (and additionally webassembly), it is designed and implemented by one of the leading IDE vendors, it can trivially call and be called from Java, it has tons of zero-cost syntactic sugar that covers the inhumane verbosity that Java buries you under till your eyes bleed and your hands scream. A well-designed language, what should have been all along.