Except they charge me the same rate if I already have my device as the person in the long-term contract, just without the early termination fee. If they have structured the locked-in person's contract to cover hardware costs then they have structured mine for that as well, despite the fact that I didn't get hardware from them. Therefore, I am paying part of the hardware costs for the people who buy phones from the provider; i.e. I am subsidizing them.
Furthermore, early termination fees are constant for all contracts. The person who got the $150 phone has the same termination fee as the person who got the $600 phone. Thus again, someone is subsidizing someone else.