"Presumably they meant Java in the client"
Android?
They are talking about his https://en.wikipedia.org/wiki/Java_applet
Which were absolutely everywhere at the turn of century.
So, yeah...if you are only thinking about web applets, which died over 20 years ago, and ignoring Android, which runs on most of the world's phones, I see why you might think "Java is dead."
Thanks to WebAssembly it is back.
>> I don't think you have any idea about the hundreds of millions of lines of Java that power the web as you know it today.
Presumably they meant Java in the client, not the server.