Some people like to play tunes, but don't have the same enthusiasm for songs, just as others like to sing but don't have the same enthusiasm for playing tunes.

Some of us are equally at home with both... each to their own!

Perhaps 'bored' isn't the right word... they just aren't interested and want to get back to playing tunes. It's nothing to do with feeling it's 'beneath them'... it just doesn't float their boat.

'Accompaniment' is a skill, and melodic instrument players do not necessarily have that skill because they often don't need it. It is more normal for a guitarist to be comfortable as an accompanist, but there are exceptions.

It would be very boring if we all liked the same thing...