Nah, it absolutely can be used as a workstation like an MPC. You can record all the internal tracks (8 recorders going at once) and export those to a DAW. You still have to work within limitations of the RAM but just to export out patterns it’s absolutely capable of doing that, just takes a bit of time to set up.
That said, Digitakt and Octatrack are both samplers but their core philosophies are so different it’s hard to call the Octrack a straight upgrade. Digitakt is more akin to the Rytm without the analog drum engines. Octatrack can wear many hats including being a DJ mixer, sampling workstation, recorder, effects board, what have you.
Using the Digitakt with the Octatrack is a great setup. I find working with individual one shots is far more flexible on the Digitakt than Octatrack while Octatrack is the king at longer loops and slicing.