I don’t see how scaling and path conventions are related to be honest, but I’m not an expert here. All I wanted to mention is that your post was factually incorrect as it is possible to create desktop applications running on JVM and it is possible to have Java-based packages - and people do all those things, and more.
As an extra 5 c I can also add that I myself would never consider creating software specifically in such a way so that it could be run as a package. A good read on why: https://drewdevault.com/2021/09/27/Let-distros-do-their-job.html:
One thing you [a developer] shouldn’t do is go around asking distros to add your program to their repos. Once you ship your tarballs, your job is done. It’s the users who will go to their distro and ask for a new package. And users — do this!