about PVE missions: the power creep of levels

it’s been some time since PVE-levels came out, and it’s no longer balanced. people with high levels are board wiping everything with little enjoyment. mid level players with just little enough health that they can still die easily yet too little damage to compete with a high level player. and most painfully: the low level Missions player, dying constantly unable to deal damage to participate.

how can this be rectified?  Well perhaps give players with levels lower than the highest a fraction of the highest persons level added to their own as such: 
66% of the highest level players health level added to those with lower levels 
_ 40% _ of the highest level players damage level added to those with lower levels 
 

this may compensate for power creep while still having an encouragement for players to purchase levels.