
If you had to pay for the increased heat use for duplicating items there would no longer be abnormally high heat efficiency when using absurd amounts of power, especially from for example dyson swarms that don’t currently generate heat without transmitters or receivers.
If you make 2 times more items you better be ready for your assembler to output 2 times more heat, for example.

Yeah I’ve long thought about adding heat to duplicators as a balancing mechanic. It’ll probably happen at some point.