There are many scenarios where this is the only way. Think of collections of pieces where you want to add new pieces from time to time (a choral book for example). Or other open projects which grow with the time (often modern composers are reconstructing there pieces for different occasions). Or think of collcections of pieces for an instrumental school.
If you insist on working a different way, then it might be better to use different software - though I can’t see now InDesign will save you any time here, but that’s your decision not mine!
Which? In all other scoring software I know you can achieve this workflow only by separating the “flows” in individual files and then exporting as graphics and importing for example in InDesign. But this workflow is also be possible with Dorico, I don’t have to go back to other scoring software. But my big hope is that this step - using InDesign - can be omitted.