I'm sorry I've a layman question here. What's the advantage we get when we host the application on a separate tomcat server (which at the end runs on a single java process) vs hosting it in docker container.

Googled few resources and the answer I got for my question is that,

1. Docker provides isolation (but at the end docker is also a process and a tomcat server is also a process) - couldn't understand the exact benefit it provides.

2. Docker allows us to be independent of OS. But again we run our applications on only few supported OS (2-3 probably) and mostly not dependent on any tools which are installed on the machine - then how this can be a benefit for container based model?

Please direct me to the right resources which can help me get better clarity David.