Dwarf Therapist was first created for assigning labors. But, in my opinion, this is now obsolete.
Not in my opinion, other than for more casual users. And it's not, per se, due to any shortcoming of the vanilla manager to do its specific task, it's because Therapist lets you cross reference information, apply scripts and use tools like control- and shift-click to select entire groups at once. Here is one example in detail of things I actually do, out of many, that are (as I am finding) painful without Therapist.
Let's say I want to get all dwarves who are badly distracted from not creating something working on glass goods. In a large fort, I may have 60 of them by the time I decide to deal with this again.
So, I go to Therapist's tab for Needs. Here I can sort all the dwarves by their current need to create.
Next, I use shift click to select all dwarves that are in the red.
Now I go back to the labors tab, and click once on glass to turn on glass making for all dwarves who have create need in the red.
This has been about
5 clicks up to this point. Of course, once they make something, they sort back to the bottom of the list on a refresh, and I periodically turn their labor off in shift-click groups so they don't hog the shop. (Simply turning it on for everybody absolutely does not efficiently cycle through those people who aren't getting their crafting in.)
However, in the vanilla game, it would be a massive amount of carpal tunnel and time I would need to burn through trying to do this without Dwarf Therapist's ability to just mass assign labor according to a sort or filter. We are talking 5 clicks in DT compared to
dozens or a hundred times going back and forth from Therapist to the Game to
individually click these guys on and off, after painstakingly scrolling around
each time to find the correct one, because they don't sort according to the things I need.
While I appreciate the excellent work that is going in to the vanilla manager, the idea that it is currently an equivalent to Therapist is not one I can agree with, and not having DT with labor functions is quite frustrating. Many things I regularly do to maintain a fort are more time- and click-intensive in vanilla by an order of magnitude (or more) beyond a handful of dwarves, even if you still use Therapist to find the information.
Other examples along these lines include things like assigning pump labor to my least fit 40 dwarves at once, grouping my dwarves by squad membership to un-assign refuse hauling from the 80 soldiers with valuable steel gear, turning smithing on for all dwarves with a preference for a military grade metal, and so on.