The general information available about these things is extremely limited online - including on third party sites like Wowhead and Icy-Veins, let alone the seemingly barren information on the Blizzard end.
As far as I can tell by reading, Echoes are exclusively available on alts by unlocking at least 1 rank 3 essence on a main, talking to MOTHER, then logging onto an alt, and talking to MOTHER.
Is there no way to access echoes of ny’alotha on a main? Do I have to get to rank 3 on an alt first?