My two cents. We all seemed to answer at the same time. --- Plus 1 to the low frequencies do not carry a melody as well as the solo instruments. If we solo it's in the upper locations of our neck Key of F at the first fret and then key of F at the 13th fret. First fret for rhythm, 13th fret for melody.
Plus they need us for the rhythm, other people take care of the melody. We are primarily a rhythm instrument. We do that playing chord tones in sync with the drummer. If there is no drummer then we are the beat master and that is best handled with notes of the harmonizing chord. How many and which ones would be best handled in another post.
Nothing new in fact same thing you said in your first post.
This is, however, an interesting question and brings up another point. I play rhythm guitar in another band that has someone else on electric bass. The vocalist count on the bass for the beat and to help them not speed up. My role with the rhythm 6 string guitar is to ---- provide what? The lead vocalist is also accompanying his vocals on rhythm guitar so he is providing harmony and rhythm for his vocals. Another rhythm guitar (me) playing the same chords can get muddy.
That's why I play mostly in another voice using one finger chords, i.e. tenor guitar. [Invalid or Expired Link Removed]
Providing rhythm and harmony while using another voice augmenting not steeping on anyone's toes. My point, we all have a
specific job to do and while doing that we should not get in the way of the other guys/gals. Back to the bass....
That is why, on bass, I leave the melody to the solo instruments
that are built for that job and I take care of the harmony and rhythm that my bass was built for.