Back clearly does not understand economics. Mining gets more centralized because of economies of scale. this is unavoidable unless you intentionally want to keep mining as a hobby. Look at gold mining. At the beginning of the California Gold Rush, anybody with a shovel and a pan could make a buck. After the low hanging fruit all got picked,you had to invest more and more capital and have more knowledge and specialized knowledge.
Back's basically saying that he doesn't want to scale up at all, but if we are to scale up it should be as little as possible. He offers valid concerns, but in practice, that means that "reasonable" block size increase means no increase.
Mining centralization is unfortunate and unavoidable but there is also limits to centralization in an open network. The barriers to entry are hardware efficiency, cost of hardware, cost of electricity, technical skill and other things like bandwidth.
Every single barrier can be overcome if the price of bitcoin gets enough. The same thing happened a few years ago when gold prices jumped so high that placer mining became profitable again. Smart rich people from lower margin industries come in and compete--But that WON'T happen if most bitcoin transactions go off blockchain because of economics.
Oh yeah. Economies of scale. Surely he hasn't heard that one before. Good on you to point this out.
I'd say you clearly don't understand english maybe? Did you somehow miss this paragraph ?
Adam Back: The worry with extremely large blocks is that they can be used to exacerbate a selfish mining attack. If you’ve got a large miner or a couple of large miners, they can create very large blocks and other people won’t be able to receive them or process them in time. So, they will gain an advantage in mining.
Bitcoin chose its parameters to make the advantage minimal so that it’s a level playing field between small miners and large miners. Right now, the interval between Bitcoin blocks is ten minutes. And the approximate time it takes to propagate, or send a block after it’s found, across the peer-to-peer network is about 10 or 15 seconds. You want the ratio between the propagation time and the block interval to be high enough, because, as a miner, while you’re waiting to receive a block, or while you’re processing a block to check it’s valid, you’re unable to mine. So, you lose money.
By having larger blocks, it’s going to take a longer time to process them. So, it’s going to favor miners with higher bandwidth or who are more centrally connected via high speed links to other miners. It gives them an advantage.
If you increase the block size rapidly, the level playing field is eroded. If it gets eroded too much, once miners are able to create blocks that only they and a couple of other big miners can mine, they can exclude everybody else because [other miners] can’t keep up.
The block size is there to put a check on these economies of scale and level the playing field.