but afterburn is 9 time outta 10 more useful that splash damage.
rocket jumping is only easy to do after you learned it, thus going back to the point of it takes time. And at least you have to aim to get kills with soldier, it's been proven time and time again that pyro can literally just spin around in circles wm1ing and you'll deal the same amount of damage as if you help your flamethrower straight.
airblast is arguably much easier than rocket jumping because while rocket jumping requires at least some understanding of tech airblast does exactly what it says it does and you can pick it up after like 10 minutes. Also let's be honest neither of these classes have only one weapon, soldier has 2 good primarys (debatably others but for the purpose of debate let's put aside preference) and pyro has 4. They both share a lot of side arms but I would say the flare guns are piss easy to use if you understand projectiles while the banners rely on the player already being good. Melees in tf2 are almost always nothing to really think about but they both have one that's actually really good, I'm not counting the market gardener because that's trolldier which honestly can he kinda ignores when talking about balance because it's a joke playstyle (not saying it doesn't work just saying in this context it can be ignored, also pyro counter trolldier, oops). So they both have one good melee, for the soldier it's the whip and for pyro it that black one I can't remember the name of. Quite clearly pyros is better because while the soldier has to hit a player (with quite wonky hit detection tbh) to gain just a second or 2 of speed, the pyro gets an all out speed boost while holding it.
I wish I could write an entire book on the balances and nuances of pyros kit but that would force me to play pyro again and honestly I hate doing that, the class feels cheap to play and cheap to win. I won't argue that soldier isn't easy to play but pyro is by far the easiest in the game.