Small blocker: Bitcoin cannot scale indefinitely simply by increasing the block size. The bigger we make blocks, the fewer people will be able to run full nodes, and thus the less secure the network is. Bitcoin cannot scale to Visa-type levels or even close while still remaining secure and decentralized. Some other solution is needed to move the majority of changes off the blockchain, and we should focus on building that rather than making blocks bigger and bigger. Blockchain can't accept every transaction forever and the sooner we make that change the better.

Big blocker: Bitcoin will probably need more technology to help scaling, but that tech isn't ready yet and won't be for months. For now, the more important priority is to drive growth, and that means expanding capacity. The block size will have to grow eventually, so let's do it now and not start dropping transactions. We should ensure 0-conf continues to work reliably for purchases. New technologies will help make Bitcoin faster and more scalable, but people should use them or not based on their own merits; we shouldn't force people to change the way they transact by letting Bitcoin itself get clogged and expensive to use.

Put differently, one view focuses more on the system, the other focuses more on the users.