I think there are two entirely different questions:
Is there any advantage to using ANY DAW with Dorico?
Is there anything special about Cubase that is integrated with Dorico to make this combination work more easily?
I think the answer to #2 is no, but I guess the drag and drop into PLAY mode is something.
#1 If you prefer composing in MIDI instead of dots, but find the DAW’s notation support inadequate, then transferring the composition (via MIDI) into Dorico makes sense, but probably not worth the hassle for 99% of users.
The more likely case is to improve the sound and realism of the playback of Dorico projects. You can export the Dorico project as MIDI and run it into the DAW and edit anything to a gnat’s eyelash. Or for a simpler (but less powerful) process, you can export the Dorico project as a set of WAVs, one for each instrument. You can put each instrument into its own DAW track and carefully control volume, stereo placement, effects etc. You can actually do most of that within Dorico without using a DAW.
I have done a little of this, but it is usually too much work for my needs. If I had a contract that required beautiful scores AND a highly realistic rendering, then I would certainly export the Dorico MIDI to a DAW, and Cubase is as good as any.
In the utopian world of the future, you will not have to face such a trade-off of time versus quality of results. The notation product should integrate more tightly with the DAW such that you can have the project active in BOTH platforms. You can change anything in one platform and have it reflected in the other, all at the click of a single button. That’s the dream, I think.