[Arnt]

"For example, an algorithm may analyze the relative position, size, and/or shape of the eyes, nose, cheekbones, and jaw" etc, says Wikipedia.

You can reconstruct a plausible face by deblurring, ie. one that looks sharp and human. But if you want to identify someone having a plausible picture with a pair of eyes in a plausible position doesn't help, you need a fairly accurate assessment of the distance between the correct eyes, and that's susceptible to loss of information during blurring.