Yoshi has made his opinions on voice programs like Discord long known - he doesn't support it because he doesn't want to discriminate against console players which the program cannot run on unless Sony were willing to come to the party (which they most likely would not). Other online games that support voice software usually have servers quarantined between different platforms (separate servers for PC, PS4, Xbone etc) which means such software is more useful in that regard.

But the fact is, FFXIV is a cross platform game and thus not being able to support voice software like Discord is simply a price that has to be paid, and that is reflected in Yoshi's stance on it I'm sorry to say.