And then there's THIS asshole

Very recently, Forge World came out with the Tau version of a Titan. 
Only it's not a machine, despite the fact that it is literally a giant robot... GW should just do away with vehicle rules at this rate, really. But that's a strop for another day.  
So this massive thing is a 600 point Gargantuan Creature capable of putting out 12 S7 shots per turn AND a 7 inch template. And of course it's Tau, so you can use markerlights to fire those at BS5 instead of it's base BS4 AND you can make it ignore cover on those too.
Now, this is 75 points more expensive than a Gargantuan Squiggoth. And could probably kill one in a single turn. 
For a hundred and something more points, you could have a Warhound class scout Titan. 
Which has less guns. 
And less shots with those guns.
And less effective protection.  
And it can explode when it dies. 
It's absolutely unreasonably priced.  

For perspective, this thing is Toughness 9. That means that if you're an Ork, take Power Klaws, and assault it, you can hurt it on a 4. If you don't kill it or don't get the charge, you need 5's to hurt it. 
5's.
With Power Klaws. 
So there's one Codex that isn't going to be able to take it on right from the get-go.  
Which is also the one Codex I actually use to play games with.  

So, what COULD take it down?  
Poisoned can't touch it and neither can Snipers, as GC's only take wounds from it on a 6.  
Fleshbane works as usual on a GC, but it's rare as hell. What even has access to it? It's typically no more than two units in a Codex, and it's usually either tucked away on a Unique character or a Relic item.   

...An Officio Assassinorum Eversor might be able to take it if he gets close, but getting him that close would be difficult - GCs can move 12 inches and still fire all the things.    

Grav weapons seem quite reliable, until you factor in it's survival chance against that.  
You come down, fire the grav, one third miss. Twos to wound means one sixth of those hits fail to wound. It then ignores one half of those wounds thanks to its Invulnerable and a further third of those that got through are ignored due to its Feel no Pain rule.  
With 10 wounds, that would mean you'd need to shoot it with about 60 grav shots to take it down.
That's 20 Grav Cannons on the move...
Which would be 5 Devastator squads.
Including the Drop Pods they need to make it down, that's 1,225 points minimum...  

It is very difficult with most armies to come up with a cost-effective way of killing it without exceeding its points cost.  
And with the amount of shots it gets per turn, it's not like you can just ignore it and play to win on objectives like you can with most other difficult to beat army types. 

It's this sort of thing that makes me feel like I should just... stop playing 40k. Whoever the hell they're writing this game for, I don't think it's me.