Thats true.
A new payment system needs to create an incentive for using it, because the network-effect of the existing payment systems works against adapting a new one. In this sense, the act of hoarding bitcoins to profit from the rate gains helps to bridge the time until there is more utility for bitcoins as a payment medium.

But it might be a problem that the bitcoin rates may continue to rise even at a point, where Bitcoin doesn't need such a supporting mechanism anymore, since it has already wider adoption. Now you might argue that such continuously rising rates simply reduce the usability of Bitcoin, and thus help to limit the demand and moderate the price rise. This is certainly true, but in practice, this process can be expected to be rough, not smooth, and will create a lot of adaptation issues, for which we (Bitcoin users community) don't have a working solution to deploy.

But I think, these are technicalities, not a fundamental issue.