JRWeb.exe is used for more than loading content in the embedded browser. It is also used for essentially all of the online functionality of MC (Facebook, Pix01, Automatic Metadata Lookup, and a variety of other components).
Any time we show a webpage, it'll be a copy of JRWeb running.
We did this so that when the web browser crashes, it wouldn't bring the program down. I'm not sure that happens much these days, but that's what made the decision for us. We wanted MC to be safe, even if the web browser crashed.
It was kind of a fun exercise in getting our IPC system up and running (the thing that let's two programs talk). That same system is now used for a bunch of stuff today.