This feature's only purpose would be to allow carrying people. How else would you justify asking for acces in a Duty for wich you're clearly undergeared ?
Define undergeared, because I can think of numerous instances in the past where someone can validly contribute to the success of a duty without being at that duty's item level requirement.

The requirements are often quite arbitrary to begin with, such as the level requirements that got put on Coil once it was added to the DF, when many many people had been clearing the Coils well under those levels prior to it.

Again there is no valid reason why such requirements should be enforced on premades. If they want to challenge themselves they should be allowed to.