Using non unreal dedicated server with Unreal game

What benefits there are in using NON unreal dedicated server, but another one - BigWorld, etc ?

Game is 3p shooter on big maps 2-10 Km. witn NPCs and items. 16-64 max players

BigWorld has nice buildin stuff for managing big worls, and a lots of stuff happening online. So it fits well MMO type games. But It also used in World of tanks and some other non MMO projects.

But as I know, Epic games has a lof of expirience on online games and Unreal server is quite fast and light.

Anyone knows what server used in PUBG ?