After doing a bit of research it seems this stems from which agency controls which maximum.  For HSA limits the IRS is in control, for ACA compatible plan limits Health & Human Services (HHS) is in control.  The IRS issued guidance in around May of 2015 for the 2016 limits, and in August HHS was more aggressive with the upper limits resulting in the $13,700 level you're seeing.

My speculation about catastrophic plans is irrelevant.