Of course to win at Deity shouldn't be easy, you have to earn it, but that's not what meant.
The smaller civs aren't competitive enough when it comes to war.
One short war and they are either reduce to a few cities or completely wiped out.
They are useless for the rest of the game, no gold, no resources.
In previous civs you could support them with techs, units, etc.
I've tried a few times to help a leader in civ5, but when my army arrived the civ was already gone.
I see this pattern over and over again where the human player ends up with one huge annoying AI.
It's just because of leaders' "personnality". It's a terrible idea. To have a fair game, all leaders should have the same "personnality". AI in some Civ games can be pretty good in building an army early (middle or late) and rushing the other peacefull AIs. Firaxis tautch them how to be nearly as good as a human player doing so. (with bonuses helping for sure) So it's ridiculous how in Civ5 some AIs won't even develop (very few cities) whereas they have Attila next door. There's a lack of concern from them. It's like it's the first time they play and don't know Attila, never read anything on him or like in real life don't have informers or spies.
Either you give them informers, either you make them know every AI personnality and how to adapt to it, either you scrap personnalities and make everybody a potential warmonger. (simplest way to program) For example they shouldn't wonder rush early if they have Attila next door, or a landlocked Rome with Iron. Question of good sense. (and information)
Those are the only means to eliminate huge steamrollers and weak useless civs, considering we want. But the fact that we want or not is relevant on how you perceive the game. Either it's mostly an experience, what glider1 calls a sandbox, and you want it to be balanced (at least as much balanced than in real life), either you see only the challenge, and in that case moving up small cubes in place of armies wouldn't disturb you, no more than any flavor or any sort, and go with the challenge adapted to the poor AI that can't defend properly with archers, because if it did, the game would be impossible in Deity with all those AI bonuses. (so AIs would have have less bonuses in Deity right from the conception of the game)
It's also a matter of how we want to play and what type of game we want to play. Do we want plenty options to make each experience funnier ? Or do we want only 2 ways to play (Tall vs Conquest... eventually) ? I've said in another topic that a sure way, if not the only one, to play Deity Civ5 was to care only about internal city/citizens management. You can (must ?) totally ignore the AIs. (beside eventual defensive wars you have to prepare yourself by building... a couple archers.
) Well so, is that the kind of game we want ?
Sure, if there would have been more options, those options could proove for some to be "too powerfull", "umbalanced" and that kind of junk. It may be fairly too easy to win a game for Let's Players. But all the other players ? Shouldn't they have more possibilities to have a better entertaining game ? No matters what difficulty you play on, if you can have a sense of cool stuff, like defending other civs by various means, or by mimicking real life History in another world that would feel real and you would have a knowledge about, or else by doing something completely crazy (on your sense), well it's right there the goal of a game like Civ. (and the point of the story & tales forum)
Then you could play another game and have a totally different but not less fun position, or if the game has not so many options (because it's only a game after all) you could go a difficulty level up to have a certitude on not repeating endlessly the same things. Something that pushes you to continue and live NEW experiences AT YOUR EXPENSE. (because you still don't know how cool is that game) Those new experiences are better obtained by having a competitive AI that you can measure yourself with. That there's a sort of "tie" between you and the AI that forces you to try to gain advantage. Those are the most fun experiences IMO. Like re-creating fierce (cold) wars, etc. and use the numerous options you have in order to try to get an edge.
It's the purpose of difficulty levels in Civ IMHO. That every player, according to his experience of the game, his personnal ability, his tolerance threshold, can live entertaining situations that he can feel because it's not just "too easy" or "too hard". But Civ5 just has not enough options and is too gamey, it just sounds like a small reality show with people killing each others. (or waiting to be killed)