The only reason I can think of is because Healers Piety stat is VERY undertuned to where they don't even consider it a role stat...

Tenacity basically does what Determination does but with one extra thing that makes it worth getting, and that is damage mitigation.

Tanks shouldn't need a weaker version of a stat that is their role stat that just so happens to be available to all roles.

The only two solutions to fix this in the long term is buff Piety so that it has the same effects as Determination and make Determination DPS only stat, or delete Determination, Tenacity, and Piety altogether and buff the actual main stats.

And before someone says Direct Hit Rate is the DPS role stat; no it's not, it's available to all Roles, it's just post Heavensward content the DPS are hogging all of the Direct Hit Rate, which they also need to delete Direct Hit Rate as stat.