The reason escape analysis is not "good enough" is why we have project Valhalla trying to bring Value Types into the JVM.

I don't have numbers at hand, but I remember the JDK Expert Group talking about this extensively in the past and why they deferred bringing Value Types for such a long time. They hoped complex enough EA can get rid of indirections and heap allocations but it just wasn't powerful enough, even with all advances throughout the years.