Hmm, slayer is useless?
First of all, I'm 88 slayer at the moment and I'm going towards level 90 slayer. In your post you said that you make roughly 50k coins per hour with slayer. You base that on what? Your own experience? Yet you said yourself that you haven't gotten past level 80.
I'm level 88 slayer and I can easily say that I've made about 200M+ with the skill. Some of my drops include draconic visage, 2 robins from a clue on a slay task, 4x dragon legs(2M ea back then), 4x dragon skirt, 12 whips, 100+ dragon boots, 4 ranger ammies, dragon junk, way too much rune junk, runes(I even bought 15k death runes with points once), ranarrs, seeds, pure essence, granite mauls,etc
I'll give you a little example... I recently collected all my loot from 87-->88 slayer and my total profit was 12M from that one level and that's not even lucky or anything
It took me around 26 hours for that one level. I average at around 460k cash an hour. That's a little bit more then your 50k an hour don't you think?
Yes, you can train with your 110k xp/h at armored zombies, but I'd rather get 50k xp/h and make 450k cash an hour + collect lots of charms. I get HP, slayer, summoning, melee/ranged/magic xp while I make a decent amount of cash per hour while you get only HP and melee/ranged/magic xp. If you take this in mind then I think that the total amount of exp gained by slayer and armored zombies is almost equal
Another reason why I train slayer is because I get bored easily of killing the same monster over and over again. Slayer gives me the opportunity to train on a variety of monsters.
Another foolish argument you made was how you're too much of a total noob to kill mithril dragon. A mithril dragon task takes me roughly 10 minutes and I got a visage drop on this task once, so it's totally worth it
It's a quick and easy task that doesn't even cost me food thanks to my great Unicorn(I got 88 summoning with charms I collected through slayer)
It's not because you're a total noob that gets numbers out of his [wagon] that a skill like slayer is useless. It's far from useless especially if you have fun while training it which is the most important thing in a game right?
Go and train afk at your armored zombies, but I play runescape to play the game, not to do something else while I'm playing automatically.