Maybe I'm misunderstanding what you're saying but applications like this tend to be horrible to use. How do you handle somebody navigating in two tabs at once? What about the back button?

Also bookmarks etc? For example if you have a view where you can have complex filters etc, you may want to bookmark this.

I guess they use something like sessionStorage to hold tab specific ids.

But something that can bite you with these solutions if that browsers allow you to duplicate tabs, so you also need some inter-tab mechanisms (like the broadcast API or local storage with polling) to resolve duplicate ids

Agreed. Also, when you paste somebody a URL, they should see what you saw... if at all possible.