User blog comment:Stabber ApSig/Mass Relays Gone, ME3 ending/@comment-3268946-20120312220251

The mass relays were the creations of the Reapers. Their purpose was to insure that organic civilization developed along the lines that the Reapers wished, making them all the more vulnerable to attack. With the destruction of the mass relays, civilization is allowed to progress along at a natural pace. The whole point of the epilogue with the old man and the child was to basically say that life is now allowed to live by its own rules and can freely advance as it sees fit. If the series continues afterwards, it is possible that they could rebuild the relays or make entirely new ones; after all, the protheans managed to do this.