Sorry canndo but you are wrong, you're missing Article 1 Section 2.
And yes it was amended, by the 16th amendment that gave congress the power to tax without apportionment among the states.
I believe Mr. Neutron was referring to the federalist papers when the federal government could not demand taxes from the states, so the relied on excise taxes and voluntary revenue from the states.
Article 1 Section 2:
(Representatives and direct Taxes shall be apportioned among the several States which may be included within this Union, according to their respective Numbers, which shall be determined by adding to the whole Number of free Persons, including those bound to Service for a Term of Years, and excluding Indians not taxed, three fifths of all other Persons.)