It depends. First, when people say that phones take pictures as good as real cameras, I think they generally mean that in conditions that are favorable to phones, they can take good pictures. If you are comparing a picture on a sunny day, with a lot of DOF, and no need to focus on a fast moving subject, the results can be very comparable. When you deviate from that, phones don't compare as well (although clever new techniques like night shot mode are helping them close the gap).
I have a lot of 11x14 prints around my house. Most are prints from pictures taken with "real" cameras, but some are pics taken with cell phones. If you get uncomfortably close to the pictures, you can probably tell the difference. But in most cases, people can't. Someone who knows photography could easily spot the pictures that were taken with a traditional camera, but they would do it less by things like resolution and more by things like shallow DOF, the use of external strobes, long exposures, smooth panning shots, and things like that.
In other words, for pictures that a phone is good at, they are easily good enough for relatively large prints. The main benefit of a traditional camera is for pictures that a cell phone isn't good at.