I'd say the bigger problem isn't from the testers, but rather from the method in which jobs are tested.
Yoshi had mentioned once in an interview that all jobs are tested on two fields: one being on a target dummy and other being in a raid environment. Although it would make sense to do this sort of testing for the overall feel of the job (dummy test) and job efficiency amidst distractions (raid test), except this still leaves out a good portion of information because solo content isn't being tested. Now I'm sure the counterargument that would be presented would be something along the lines of "it's an MMO, you should be doing things in a group", but not only do a sizable number of players do content solo (especially open-world content), but some content like quests have don't give the option of doing things in a group.
The removal of Sustain is a really good example of this. The reasoning why it was removed was along the lines of "it wasn't being used that often"; a perspective only gained from data acquired from group content where pets typically take reduced damage from major attacks and get enough offshoot heals from AoE healing effects that pet jobs could get by with not having to worry about using Sustain....until they have to fight in open-world or forced solo content, where pet healing abilities such as Sustain are the one skill keeping what would be a pathetic pet from getting trashed in three hits to being able to adequately help the almost-as-pathetic caster.
In short, it's that lack of solo questing perspective that make FFXIV testers seem substantially more incompetent than they probably are.
