It's all a matter of what question you're trying to answer. WAR represents the sum of the average value of the events a player has generated. For example, a home run is worth ~1.7 runs on average and that's the value that gets worked into WAR. WPA represents the changes to game-state that occur when the player is standing on the mound/in the batter's box. Like WAR, but with more context and no defensive value. If you compared the two, you would get the game-contextual value added by the player, not including defense. Perhaps interesting but not meaningfully valuable.
I generally see value in stats like WAR; they serve their purpose well and can be used in hypothetical scenarios and summary scenarios (Player A is an X WAR player, Player B has compile Y wins in his career, etc.).
WAR doesn't tell us what a player's true-talent is, although it is much closer to illustrating past true talent than other, less comprehensive stats. You can use projections to be informed of how good a player like is, free of bias. A good projection system weighs the available public information properly to come up with how the player is likely to perform going forward. It will strip out the noise associated with defensive numbers and fluky peripherals.