Um...
Once the dike is around you should be working all your cities tiles
Quite a big assumption, given health caps. Rare are the games I peek into where the player has size 20 cities around 1500 AD for all cities. Maybe a few.
and have banks and grocers everywhere as well as the wall street. This is when the CE comes into its own and then
City specialization = not banks and grocers EVERYWHERE. We also suffer somewhat here as to whether the extra hammers are huge or not ---> hammer cities are likely to be smaller and far less likely to have 0 health trouble allowing the working of a marginal tile.
This is when the CE comes into its own and then dikes caps it off, making the dutch the best late game civ to be IMO.
1. CE and SE are close-to-useless terms
2. How does a marginal hammer improvement benefit cottage spam? You want your multipliers first, no?
3. All of this assumes lots of coast or coastal cities in the first place. The dike is strictly equal to its stock building when inland.
And the reason I call this the dike orgy is because the last favorite UB poll named it the top UB, usually favored because it's "so strong".
But, if you're running a fractal or shuffle map, I can reel off so many UBs that are better it isn't funny:
1. Sac Alter, which as mentioned can potentially outproduce the dikes on water maps, and always outproduces them on land maps. Oh yeah, it's got a reduced hammer cost too.
2. Zig: Early EP and cheap cost
3. Ikhanda: dominates w/ corps, and allows for aggressive early expansion
4. Hammam: + 2
early on is a big deal, especially on a tech you'll be getting early
5. HRE UB: Earlier and like ikhanda dominates w/ corps
6. Trading post: naval mobility is a big deal on water maps, and you have it w/ galleys on.
7. Hannibal's UB: Again, it's a lot earlier. The extra trade route could be as much as 8-10 commerce on something you'd build anyway.
8. Terrace: Skip the monuments, chop this and grow
9. Madrassa: Early culture press is nice on its own (gotten in time to double, it can even content with creative's culture press). If you need prophets or just fast GPP even better.
Note the above isn't a ranking, just a list of UBs that are all frequently better than the dike, and I don't think it stops there. Granted, in any given game the dike *might* outperform them, maybe. However, the fact that any of these could easily be superior (hell, on land maps virtually every UB is superior other than the other water ones) definitely dampens the whole "overpowered" question. This is why it's the "dike orgy". Even though it's a decent UB, the love it gets makes it easily the most overrated of all UUs/UBs.