Prior to this change, receiving Echoes relied on another character on your account having a Rank 3 Essence that the character in question did not yet have. So if your main had the Rank 3 Essences but your alts did not, then the alts would have been the only ones acquiring Echoes.
Now onto the newest change:
In order to acquire Echoes now, your character must have their legendary cloak. The sources & rate for acquiring Echoes have been increased. Of course, the costs for items from MOTHER have also increased.
More info about the recent changes, can be found in this thread: Targeted Corruptions and Faster Cloak Empowerment