When using an viewscreen on a digital camera, trying to frame the image properly usually involves rotating the camera on an axis centered on the camera. When using a viewfinder, it usually involves rotating the camera on an axis centered on your head, which is very similar to simply looking around. You're reusing instinctual movement. If you watch most people trying to frame with a viewscreen, they're clearly expending effort trying to figure out the proper direction to move the camera. Practice would certainly help with that, but nothing will come more naturally than just using your existing skills.

Relatedly, LCDs viewscreens seem to almost always lag a fraction of a second behind the real action, which seems to result in a boat-rocking action when trying to frame. Of course, that would be true of an LCD viewfinder, too.