Famous example of how badly this works is Jira. Want to look something up in another ticket? Bad luck! You need to close that ticket, then open the other one, then memorize or copy the info you need, then close that ticket, then open the original one again. At that point you are better off circumventing the whole shit UI and clone the browser tab. Which ultimately leads to having a dozen browser tabs open that one needs to cleanup later. Add to that the general incredible sluggishness of Jira, and the massive amount of things loaded when you load any of its pages, and you have a recipe for the disaster that thing is.