Obtaining Rank 3 Essences on Alts

Right, but do you have the healing and tanking variants from each of those sources? For example, Breath of the Dying is a DPS essence, and the same source (initial 8.3 quest chain, R3 from Rajani rep) also rewards Touch of the Everlasting and Spirit of Preservation. Due to the hotfix, simply having Breath of the Dying at Rank 3 now makes it so your main can also purchase both Touch of the Everlasting and Spirit of Preservation directly at Rank 3 from Mother for Echoes, even if you’ve not acquired Rank 1 or 2 for them from the Rajani quartermaster. The same goes for the other grouped ones (list of groups can be found in the post I linked: More Flexibility with Essences).

So unless your druid also has every healing and tanking essence at Rank 3 that comes from the same source as any DPS essence you have, your druid can now acquire Echoes, and can use them to purchase said tanking and healing essences.