You're conflating purpose with power. "Promote the general Welfare" doesn't create unlimited power. The power comes from the Constitution. The point is that once you are interpreting those powers, the Constitution's stated purposes are relevant to what they mean and how broadly they should be understood.
Nor was "general Welfare" some contentless phrase at the Founding. Protection, safety, prosperity, happiness, and the well being of the political community were all part of the contemporary vocabulary surrounding the public good. As Madison wrote in Federalist 45, “the public good, the real welfare of the great body of the people is the supreme object to be pursued”.
All government powers carry some risk of abuse. But, as Joseph Story put it, “Neither rulers, nor any other functionaries, much less any private persons, have a right to cripple it, because it is according to their own views inconvenient, or dangerous, unwise or impolitic, of narrow limits, or of wide influence.”
Nor was "general Welfare" some contentless phrase at the Founding. Protection, safety, prosperity, happiness, and the well being of the political community were all part of the contemporary vocabulary surrounding the public good. As Madison wrote in Federalist 45, “the public good, the real welfare of the great body of the people is the supreme object to be pursued”.
All government powers carry some risk of abuse. But, as Joseph Story put it, “Neither rulers, nor any other functionaries, much less any private persons, have a right to cripple it, because it is according to their own views inconvenient, or dangerous, unwise or impolitic, of narrow limits, or of wide influence.”