The discoverers have some theories for why they found this extremely distant star hub. The hydrogen reionization in its era may have been patchy, making it feasible to spot some galaxies but not others. Also, EGS8p7 may have been populated by exceptionally hot stars that created a giant hydrogen bubble and broadcast the galaxy's presence. Whatever factors led to this rare sighting, it's clear that humanity's understanding of the oldest galaxies still needs some fine-tuning.
[Image credits: NASA/ESA/R. Ellis (Caltech)/HUDF 2012 Team, Flickr (top); I. Labbé (Leiden University)/NASA/ESA/JPL-Caltech (bottom)]