You didn't mention WHAT you wanted to click, hold, and drag. I'm assuming you meant the quick-section line, which in the C3D case would be the alignment.
If you can see both the plan view and proifile on your screen (viewports from a layout?), you can do it with C3D.
Quick section is more convenient, though, and I would agree that it should be ported to C3D before we can consider C3D a full replacement for LDT. Daylighting and the 3D Polyline routines, too!