FANG interns aren't coffee-runners; you can't give them work you wouldn't give to a real junior engineer. First: doing so undermines your efforts to recruit the intern. Second: doing so undermines your efforts to evaluate the intern. Third: doing so wastes a valuable eng resource you could deploy on something worth launching!
The real problem for Reader was that it wasn't worth any engineering effort (because it only had a couple of million daily active users).
If I were an intern at Google and it was my job to maintain Reader I would be ecstatic. Hell, I'd happily do it now as a senior engineer. Why would I rather do a bunch of bullshit on a product nobody cares about when I can work on something I know people deeply love? Can you think of something that would have a larger impact than maintaining Reader?
This mentality is entirely the reason why large corporations can never do anything apart from their core business, and why they always spend billions acquiring startups (which usually fail to integrate into their business). They just fundamentally are incapable of creating anything new, and when they somehow do it the incentives are so misaligned they shut it down and the only thing they get for their efforts is making the public rightfully hate them.
The real problem for Reader was that it wasn't worth any engineering effort (because it only had a couple of million daily active users).