Imo, ppl sometimes focus too much on copying instead of bringing original material to the plate.
Sampling is something that hiphop started out with though. Nowadays, sampling for professional use is a *****! Too much copyrights and whatnot. Getting permissions or even getting in contact with artists is sometimes impossible.
Copyleft material and creative commons licensing is something of nowadays that I like a lot.
For non professional use, everything still goes, as long as you don't put it online for the public.
As a final thought, ppl isolate themselves. There's probably tons of ppl that can properly sing right in your neighborhood or social circle.