Why was the 18th amendment needed?

[True Federalist (진정한 연방 주의자)]

At the time of its passage, the expansive use of the commerce power to cover intrastate activity had not yet come into vogue.  Also, the existing state regulation largely made alcohol sales an intrastate activity anyway.

[True Federalist (진정한 연방 주의자)]

Nothing in the 21st limits Congressional power. It does grant the States some powers over alcohol that would otherwise be limited by the Dormant Commerce Clause.