The advantage of contributing to a pension over making a mortgage payment is the fact that the pension fund compounds tax-free.
This is overly misleading imo as it doesn't cover other significant financial advantages e.g. tax-relieved contributions, employer matching (not always available).
It also doesn't cover the behavioral advantages(us humans are not rational)
-folks can't spend the money in pension till retired, regardless of how tempted they are
-with a lower mortgage most people will be more tempted to increase their spending (which will reduce what's available in retirement).
-with a lower mortgage many people will be tempted to trade up, often resulting in more advice to not fund pension, but regardless ultimately resulting in asset richer cash poorer retirement. And also with less ability to help kids and grandkids (until we die).