This is generally true, but I think you might be out of date. About 15 years ago, the US government passed a law that specifically prohibited the melting of pennies and nickels for the purpose of selling the materials for profit:

§ 82.1 Prohibitions. Except as specifically authorized by the Secretary of the Treasury (or designee) or as otherwise provided in this part, no person shall export, melt, or treat: (a) Any 5-cent coin of the United States; or (b) Any one-cent coin of the United States.

https://www.law.cornell.edu/cfr/text/31/82.1.

Click "next" on that link for the special exceptions, which do allow for modifying small amounts of these for jewelry or decoration.