So you don't use force points nor Dark Side points? Both are metagame.
That's not accurate. The Force and the Dark Side are concepts within the setting and the mechanics model those. You could argue the same for Doom (it models a sense of Doom that Conan once referred to) but I think the concept is clearly less embedded in the setting and, given how it operates, is more obviously of a metagame nature. I think the same is true with Inspiration, which though it could be argued as being actual inspiration, how the mechanics operate make it clear that it is designed as a metagame mechanic.
However, I think this all misses the point. There is nothing wrong with metagaming. It is a matter of taste only. Though the D&D5e DMG correctly warns against the players using OOC knowledge, expanding that statement to say any metagame mechanic is bad goes way beyond its intended meaning.
Its also important to note that we are talking about a GM tool here, not a player one. If you take some of the arguments here to their logical conclusion then a GM choosing to run a module based on its prescribed levels being a better challenge for the PCs would also be bad as the GM is referring to mechanics outside of the setting's conceits. The same is true of encounter building rules, which the GM uses to plan out there encounters. I am sure that there are RPGers who truly believe that these kinds of rules are bad too, and are happy to add a Adult Red Dragon to their 1st level PCs wandering monster table, but I would expect the majority of RPGers see that such mechanics add a lot of enjoyment to the game.
To reiterate, the Doom pool is intended to do a couple of things:
1. To provide the GM with a bennie pool equivalent to the PCs. It does this well and helps the GM with NPC resource management.
2. A gauge to help the GM evaluate when to push harder, as well as a visual countdown clock (which is genre appropriate) for the PCs. Again, it doesn't force the GM to play that way, such as in FATE, and there is a robust RPG system that sits alongside it operating as you would expect.
Again, if you hate any metagame mechanic, even action points and encounter building rules, then Conan 2d20 is not for you. There is really not much more to say that just isn't a repeat of your concern ad nauseum. However, I don't think that purist position of these mechanics reflects where today's hobby is as a whole.