Just about all grenades are OP as long as they hit a target within their closest AoE. Grenades with burns are no exception, but grenades with the lightning-chain attack have a better range than ones that simply explode, like the combustion grenades. The fact that it can have the burn DoT added makes it all the more dangerous and effective. It's similar to how you would compare Thorn to other hand cannons. Farther range and a DoT effect.