Why are local bands and unknown musicians so bad?

[Vermilioncore]

I remember at a metal concert this guy showed me a link on YouTube of his band playing but it was dog shit and sounded like garbage. He said they were trying to get a record deal. How come big bands sound good and catchy but random local people make shit music? I felt like telling the guy “sorry man there’s a reason your music isn’t doing good, because it’s shitty”