Wait a second. The biggest problem here with a crypto system that is not open is not that "it may have not passed through a lot of eyes", it's that it may have not passed through EVEN A SINGLE EYE. The closed system could very well be "we xor this with ILUVPUPPIES repeated ad infinitum" and very few people would the wiser.

An open system at least means _you_ can have a quick look into it. Every other advantage is not guaranteed, but with the amount of pure snake oil out there this one guaranteed advantage is friggin important.