Sometimes games are made to be fun, other times they’re made to make money. But motivations aside, no game is fun for everyone, and as soon as you make it more fun for one group of people, you make it less fun for others. Blizzard saying that it’s for everyone is more of a marketing thing to encourage casuals to try it.
Plunder is a progression reward towards the FOMO cosmetics; it is the main objective for people who don’t enjoy the gameplay. A PvP player would say the main objective is to be the last person alive (which gives the Victory screen).