Suppose you are in a group playing and the singer can only sing the song in a key you don’t normally practice it in.
If you know how to find a melody (or improvise) in the different positions (1st, 2nd, 3rd…) it is far easier to play along.
Taking a break/tune/song and learning it out of the different positions (and finding points where you can switch positions to attain certain sounds) greatly enhances your ability to play along. It’s about more than just learning scales…As you noted yourself in another thread: "Lately I have been trying to spend at least 30min each day… learning to play on different parts of the neck, (learning the pattern) That has been a pretty big help for me."
Using Liberty as an example…what if it’s being played in C? Will you capo to the 10th fret?
If you play w/o capo Part A down on the G & D strings (same fingering) you still have to go higher and change positions for Part B…It’s not wrong, but it is a change in the sound of the tune , as is the key change.
Being able to change positions makes it fairly easy for me to play Liberty in C and keep the A part as the high part.
As a side note: Normally in the key of D the first melody note of Liberty is an F# …are you using the A as an intro note? If not I’d be interested to hear what your using as a melody…I’m always up for learning new ways around things.