Comment by pyre

True, but if you 'convert' a large collection today, then you skip the possibility that Apple will implement anti-piracy features in the future. With Amazon and Google, no one can really be sure what the status is right now. Especially since you are uploading bit-for-bit copies of the files to those cloud services.

In financial terms, Apple is running an exchange, while Google and Amazon are running a safety deposit service. If someone looks in the safety deposit and finds illegal items, you are caught. If someone looks in Apple's music locker, you only see Apple's AAC-encoded content (though I guess they didn't cover how that works with music that you didn't buy through Apple and they don't carry on iTunes).