Interns don’t do maintenance work in general. They build new stuff, often flashy new stuff that never ships [1], because the intern program is about evaluating potential hires and giving them a great experience so they want to come back. Giving interns tedious unrecognized maintenance work is a great way to convince them to go elsewhere.

Source: Microsoft employee

[1] The goal is still to build features that ship, but because they get new, shiny stuff, sometimes it’s speculative development and the winds shift before it goes out the door.