I don't really go for diplo, and maybe the meta for diplo allows fast wins. In that case this wouldn't apply.
But, assuming you are marking them down because they love to pollute with industrialization- once you have global warming mitigation, you can simply conjure infinite diplo favor because every one of those projects gives you 50, you have tons of surplus production everywhere, and they build fast. I can pretty easily overcome the entire world's output and push the accumulated emissions back to zero all by myself with a peaceful empire, and then win all votes.
You're wrong, pollution is not a problem. I should have given reasoning before.
There are two ways of gaining diplo victory:
- military path, eliminating most of the civs, so civs with strong unit / strong bonus to ammenity-loyality / strenght are good. Zulu with early corps/armies and bonus loyality is a MONSTER diplociv.
- peacefull path, when you need either:
a) source of raw diplofavors (America, Sweden)
b) cash cash cash and even more (Mali, Cree, England, Persia etc)
c) city states as allies (Greece, Hungary, Georgia)
or any combination of it.
Germany gets no bonus to any of it. Its UU is nonexisting. Military card gives some flexibility in units production, but sincerely not gamebreaking and not making them better at war than most civs at any stage.
What Germany gets instead is very strong combat bonus vs city states, it is a sin not using it, German uniques wants you to eliminate important factor of DV. And unlike killing whole civs, grevviances from attacking / killing city states are harder to cancel, so no DF from CS, harder DF from alliances and so on
What I want to explain is that if you want to play Germany in a way they are designed, you are in bad posyion for DV. You can still do well not killing CS, but why not use the 2nd best german uniques?