Blizzard wanted to take some ideas from FF14 where there are support classes that buff the group.
However, FF14 has a community that doesn’t mind supporting each other while WoW has a community where most people are actively hostile to each other. It also bans DPS meters. I think if WoW didn’t have DPS meters, maybe a support class could work, maybe. But people would still use third party tools to math things out and optimize the fun out of the game.