That is actually part of the basic functionality of EOC. The idea is to give you a consolidated overview of all of your SolarWinds servers, and then to allow you to drill down to specific nodes on specific servers if you need to.
Someone else on the forum might be able to provide some of the best practices and use cases they've utilized in their environments, but I thought I'd let you know this is expected behavior so you're not left wondering whether you've done something wrong.
Keep working with it, and I hope you'll see it's value.
Middle-click works great for me. I usually have EOC open in one tab and another tab with a custom view on our biggest NPM. When something goes down at another site I just middle-click (open in new tab) on the EOC page. That way I never have to leave the EOC page.