Im sorry that the brand new system that was just released does not instantly match up to the abilities of a real player upon release.
Play at any sort of lower level than Adoulin and you will see they are very powerful, its only once item levels are introduced to the mix that they begin to fall so short of the mark and reach the point of being worthless, even then, its not quite true. Using melees in high level areas like Kamihr you will not see them do much due to the fact they have not been fixed for that level yet, their accuracy falls off very poorly and their attack is seemingly horrible with them hitting for very low numbers such as 50s with daggers in the case of Nanaa.
However, if you use Shantotto, Ajido, and Kupipi as your party you can see a nice difference so long as you afford them the MP they require. I soloed merits for Ark Angels earlier for instance and for my party I used these 3 NPCs, so long as I kept them Refreshed full time, Kupipi made healing effortless, paralyze was never on for more than 3 seconds, and my BLMs dealt enough damage to combined total up to about 70% of my overall damage because they spam nukes for 1.5~2k.
So long as the updates coming in February(which are supposed to be fairly large it seems) do enough to improve them at level 100+ and the AI improves, we could easily see this become dual boxing for people who don't normally. Till then, its a hell of a lot better than having literally 0 assistance at all like people had before Trust was added.