Not exactly e is quite unique in this matter, it's not really about the growth rate but rather about the "divisibility" of the currency in regards to spending. Base 2 is the second best choice for a physical currency, best is 3 however in our case we can exploit the base e which for a physical currency is just a idealistic assumption but in our case a practical possibility.
That sounds very vague to me. How does base e make a cryptocurrency more divisible than base 2?
If the value/block was increasing and the target spacing was staying the same then you would have exponentially more coins as the difficulty increased.
I assumed you would have the target spacing decrease so there was a constant number coins being produced.
No, I'm not trying to make production either exponential or constant. If I wanted exponential I would use a linear relationship between reward and difficulty, like 1 coin per point of difficulty. If I wanted constant I would just make the reward 50 coins forever and be done with it.
Yes, that's what I'm saying.
If you have one block every ten minutes, then you have one block every ten minutes.
If the difficulty goes up, then you have more coins/block, but still one block every ten minutes.
This means that you either expect the difficulty to stay constant, or to go down. Otherwise you will have an exponentially increasing number of coins.