Because the singer can be distinctive - the rest are replaceable. Any competent drummer can be trained to do the drumming. It is not always possible to find a replacement for the singer, because his or her voice might be distinctive or their face and personality might not be 100% replaceable.
Generally the people who get the most credit are the ones who are indispensable to the band, who can't be replicated. The main song writer/writers are, if talented, unique and can't be replaced. The singer has a distinctive face and is the one you focus on because they are the one singing and we are naturally drawn to human sounds.
But the Guitarist? The Bassist? The Drummer? The.... Tambourine-ist? The.... fluter? He or she can be replaced, if that's all they do. Just hire another guitarist who can play well - and there's plenty of them around if you have the money.
Generally the people who get the most credit are the ones who are indispensable to the band, who can't be replicated. The main song writer/writers are, if talented, unique and can't be replaced. The singer has a distinctive face and is the one you focus on because they are the one singing and we are naturally drawn to human sounds.
But the Guitarist? The Bassist? The Drummer? The.... Tambourine-ist? The.... fluter? He or she can be replaced, if that's all they do. Just hire another guitarist who can play well - and there's plenty of them around if you have the money.