This was just a random example. I'm sure if you take a statistically-significant variety of PDFs and benchmark rendering quality, speed and features in all PDF

This was just a random example. I'm sure if you take a statistically-significant variety of PDFs and benchmark rendering quality, speed and features in all PDF viewers out there, PDF.js won't be any closer to the top; Chrome's viewer will certainly not be the very best but not one of the worst either.