As I said earlier, its chief value is as a sort of overview stat. It's a quick-and-dirty analysis tool, a conversation starter, a scope-narrower, or a point-of-comparison basis. It's not meant to be an argument ender unless it points to an obvious conclusion. Someone arguing that player X is better than player Y can easily have their point bolstered or refuted if someone mentions that X's WAR is 3.0 points higher/lower than Y's. Or you can say that Z from 1980 had a similarly impactful season to A from 2015 and start out by showing that their WAR totals were within 0.3 of each other before you break down the guts of comparison.
That's its use. As a way to stop people from having to trot out "well he had X, Y, Z, A, B, C for average, OBP, HRs, defensive impact, etc" every time you want to talk about a player's overall impact. Becuase 1 number provides a more focused piece of evidence or example than making people wade through a half dozen numbers and contextualize all of them.
The misuse generally comes from trying to use it in close races. Saying that X had 3.5 WAR and Y had 3.7 WAR last year is meaningless because it's so similar. It's like trying to argue that one guy was better than the other because he hit .315 over .303 or that a pitcher was superior because he struck out 21% of batters he faces whereas another "only" struck out 19%. Those arguments need more analysis because you have to differentiate the players and break the ties/close races. and WAR isn't designed to do that.
Also there's the common complaint about how different places use different versions of the stat. And yeah it makes things confusing because you might sometimes have to ask people which version they're using. But it doesn't make it "wrong" as long as you're using them in a consistent manner.
If you asked 5 bakeries to make you a chocolate cake there's no guarantee that you would get 5 identical cakes. You probably wouldn't. But that doesn't make any one of them be less of a cake than the rest. I mean unless they show up with a box that contains an apple pie with a Hershey bar sitting on top of it. WAR is a category of stat, akin to "chocolate cake" being a category of baked goods with room for variance. Whereas something like ERA is "toll house cookies" or OPS is "traditional black forest cake" and are both specific recipes with particular ingredients and steps (which doesn't stop people from modifying them, but at that point they become modifications and not "true" representations of that good)
and I think I need to stop with the baked goods metaphor before I get hungry
