SMD vs COB

Reflow soldering (the process of attaching the pins) and epoxy potting (the process of protecting the pins) are risks inherent to the SMD manufacturing process. 

Even with the very best equipment available, the maximum accuracy that can be obtained is 99.99%. 

For a P10 display this mean 40,000 x 99.99% = 4 hidden problems per square meter. This does not even take into account the hidden danger of oxidation of the pins prior to the potting process.