There have been many "singers" over the years that don't seem to carry a tune.
We have heard that about how Mr. Dylan, Mr. Young and many other artists can't sing?
What about the soul of the tune. Joe Cocker (early stuff), Adel, Eric Burdon, Ray Charles, Van Morrison & many old blues singers. They all have our love from the way they sing.
Johnny Cash wasn't a tuneful singer but is much regarded.
Soul counts for much. Frankly, more than pitch.
There are many singers with no soul. Pitch perfect, but empty.
That said, they can perform in a way that makes them stars.
So what is it?
Some care for tone, or execution of scale, others the execution of soul.
There is more to "singing" than tone & tune.