The harmony part has always seemed to be what has made or has broken a song, despite the skill level of the musician.
I should have myself have sung to karaoke samples if I wanted just the professional approach. At least according to proclaimed professionals on the net. Even though I don't have a natural singing voice. I would rather bomb out trying other things instrumentally. Vocalists are also very instrumental.
It may be a matter of finding the right environment for that other then what you find to be your misgivings.
But I say that wanting other vocals and harmonies in my posted recordings other then my own.
Everyone has their own definition of good in their expression with that though