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.
The small block argument falls at this fist hurdle. If bitcoin gets bigger, it - well -
Gets Bigger. There is no escaping that fact. If people want bitcoin to be a major player as a payment option for millions, then they will almost certainly not be able to run a full validating node on any shity 486 they have lying about the house.
And please don't insult us by crying "But segregated witness!" - segwit will require all full validating nodes to transmit and store as much, if not more, data as bitcoin currently does.
The fact that small blockers trot this non-argument out as a cornerstone for maintaining the limit is a clear indication of how untenable their position is.
But Lightning!
SegWit is the foundations for Lightning.
Segwit soft fork, followed by Blocksize hard fork.
Yes, all 3. SegWit. Then Lightning. Then Blocksize. or maybe swap the last 2, depends a bit.
Lightning is the only credible plan to scale up to billions using Bitcoin.
Who wouldn't be in favour of implementing the plan that actually scales up?