This is more of an old web, and because of bad design: keeping state of the app on server, rather than in the browser (or are you referring to limiting open in new tab?).
But yes, I hate the new web too (sometimes).
But yes, I hate the new web too (sometimes).
There are other apps, that are even worse. Allowing something to open in a new tab/window but identifying that there are multiple windows open and just disabling all but the main window...
I don't understand developers that do this. I always felt that multiple tabs is a strength of the web. They worsen it somehow.