Non-coerced transactions are win-win, by construction.

Each party gets something they value more and is better off by participating.

This is the raw alchemy of emergent value in an economy.

The main problem is: a transaction can be entirely positive to the participants but have negative externalities so society is worse off.

A transaction that both parties like and with no or positive externalities is morally good.

One that has net negative value when accounting for externalities is bad.