Yield Farmers are attracted by yCurve's extremely high APY. They definitely want the whole set of benefits. So what will they do?
They cast yCurve and deposited it in the farm YFI. Later, they discovered that the deposits in the Balancer pool could breed more YFI. They want to join, but most people don’t have any YFI yet.
This is the point. Since YFI/yCurve is a 2%/98% Balancer pool, people will not immediately feel friction or loss. But only using yCurve to increase liquidity has the same effect as using yCurve to buy YFI (what?). In short, whenever a new YFI farmer joins the pool, she deposits yCurve as if 2% of it was used to purchase YFI.