Facing a queue of two tickets, or ten tickets, or one hundred tickets, the application team has to decide what to do first. This is where things start to unravel for an idealistic, full-stack, “you break it, you fix it” devops team. Which issues are causing business damage? Which are the most time critical? Which can be deferred? How much time should we spend on this stuff at the cost of moving the product forward? This is the stuff that Service Management ought to be able to provide.
No matter how effective the first line of support is, some issues will get to the application team. Those issues will vary, as will the level of pain that each is causing. Triage is required, and that is only possible if there a clear understanding of the business and customer perspective.