How would they figure out if you did or did not own two PS3s? Honestly it is because of multiple accounts, multiple systems, reliability and some others such system of abuse exist for the 360(360 being different) and PS3. With the lets say DS, PSP, IPhone, Android Phone you could have it work on only one system because the consumer had a reliable piece of hardware, you had a system to shift content over just in case it failed and the consumer most likely has only one DS, PSP etc of those devices with one user. Of course sometimes there were two users but even then you had multiple saves and other things in place for most games. The 360 also has shared content problems so I say it is mostly a console system problem which seems to have no easy way to fix,
The Wii locks it to one system which has it's own share of problems but Nintendo is willing to transfer the content for a price just in case of system failure.
The Wii locks it to one system which has it's own share of problems but Nintendo is willing to transfer the content for a price just in case of system failure.