The problem isn’t so much that the game as a total is too complex, it’s more that the time it takes to learn all the complexity is a lot longer than most new player will stick around to learn it.
A lot of player nowadays have been playing for a decade or more, and the complexity is second nature to us. But for a brand new player, it’s a LOT to take in. ESPECIALLY in PvP. There’s like 100 different cooldowns you need to learn and know how they interact with the other 99. It’s insane