Because this list isn't really an objective list based on HoF results or anything like that, but on one person's opinion.
I'm not a great player but I've played enough Deity games to see that Shaka is formidable even when the AI plays him, and in the hands of a seasoned Deity pro he is completely OP.
My Deity win with Shaka was so easy compared to any of my other Deity DomV games. Basically, the difficulty with other units is that their 'edge' doesn't last very well. For example, XBs get fairly stomped within 20 turns of you upgrading your CBs. But Impis last a lot longer, and you can have HORDES of them without crippling your economy, and if you go Honour Opener > Liberty Opener > Left side of Honour > Left side of Liberty > Right side of Honour > Right side of Liberty, AND get SoZ and Pyramids, you have a good shot of winning before Artillery, which I've not managed with any other civ.
So yes, vastly underrated, and yet more evidence that this list is silly. And for those that complain about how Impis are melee, please understand that just because you're building Impis DOESNT mean that you WON'T also build ranged units. It's just that what makes Zulus better than vanilla warmongers is that while the latter puts meat shields ahead of the ranged units, and they get shredded to preserve the life and promotions of your ranged units, the Impis can hold their own until the Industrial era, and many of them will become upgraded almost unkillable and you'll still have your Range + Logistics behind them.
I find it crazy that I have to type all this to extol the virtues of Zulu domination and Swedish CV. You guys should just PLAY these civs. I'm no Deity wizard and yet these are easy civs to play with.
While I agree that Zulu and Sweden are powerful civs, I think the issue with this tiering system is (and has always been) that certain civs are better at certain *types* of victory than others, and certain maps, and certain starts, etc. etc.
Any list that doesn't break up the rankings by difficulty level, victory type, map type, map size, and even game speed, is going to average out all the awesomeness of individual civs, and the only civs left on the top tier are going to be *generically* good civs. (Which aren't necessarily the best ones for any given situation)
However, since the stated goal was to do basically that, you'll just have to accept that Sweden and Zulu are not "top-tier" by the stated definition.
Also, it's totally a matter of opinion. I would put Attila as top-tier even under the OP's restrictions. The OP isn't specifying "fast" wins, but "reliable easy wins", and nothing is more reliable or easy than wiping out your continent by t100 and having all those CS to yourself, + a few wonders, no matter *what* the condition. However, Attila suffers on small island starts. And the OP has homogenized this list to include ALL map types. So, Even though Attila is probably the easiest civ to consistently win with on MOST map types, he isn't on ALL, and so he gets put down to lower-middle tier. Eh, to each their own.
Ideally, the HOF *would* be the indicator. But, the HOF entries are heavily influenced by 4 factors which make it not a good sample set.
1) Gauntlets.
Gauntlets determine the most-played civs more than any other factor. Gauntlets also reward fastest-finish, which skews the results further. Gauntlets are almost never held on Deity, level, resulting in waaay less Deity entries.
2) Insufficient sample size.
Even if you don't take into consideration #1, there just aren't enough HOF entries.
3) Turn-of-victory & Score are *not* an indicator of how easy the win was.
I would argue (and have many times) that Time-of-victory is *usually* an indication of how easy the win *could have been* if you weren't going for a speed record. The best argument here is simply this: The AI *struggles* to win before t315 in BNW. Meaning that if you can win by t250, even if you barely pulled it off, timing everything just perfectly... well, you could *easily* have won by t300 in the same playthrough, with significantly *less* risk.
4) Re-rolls. The HOF is full of 5-salt starts, or perfect Petra starts, or 7-fishing boat coastal capitals with 3 NW in the first 3 cities. Not a good indicator of a "typical" game.
That being said, there's a *damn good reason* Attila has the fastest victories in the HOF. If you don't think every t110 domination by attila couldn't have been an eventual EASY Science, Cultural or Diplomatic victory, you're fooling yourself. ;-)
Ok, I'll shut up about the Attila thing for another few months now.