A second reason that the "bring your best before the Lord = finest quality musicianry" is mistaken is because it is wrongfully exclusive and/or oppressive. That is, it's yet another form of elitism.
Moving toward spotlighting and/or privileging highly-musically-skilled-people insinuates (at least indirectly) certain things about people who are not musically skilled. Spotlighting only the best musicians makes it more likely for certain conclusions to be drawn. Conclusions such as:
1. If i'm not musically gifted, my brethren don't want to hear me sing; so i
should either not sing, or not sing loud enough to be heard.
2. If i'm not musically gifted, it's more important that i listen to those who are
than to participate myself.
3. When singing, musical skill is equally or more important in worshipping God
than the disposition of my heart.
4. If i'm not musically gifted, i am less capable of edifying my brethren by
5. If i'm not musically gifted, my edification of others is less important than the
edification offered by those who are.
Be careful to note what i'm claiming. i'm not saying that musicianry-emphasizing-churches believe these things. i'm not saying that musicianry-emphasizing-churches want these things to implied by their worship services. i'm not saying that musicianry-emphasizing-churches aren't loving and well-intentioned and all that. What i am saying is that musicianry-emphasizing-churches create an atmosphere such that these subtle messages can develop (consciously or sub-consciously) in the minds of members.
My home congregation is a musicianry-emphasizing-church. i don't think they're doing anything intrinsically wrong by microphoning certain people. i don't think it's a sin for certain people to be heard louder than others. That's not what i'm saying. What i'm saying is that this practice is conducive to creating an environment in which some people get left behind. And Christ was not in the business of leaving people behind, nor should His church be. i've heard members of my own congregation speak as though the singing on a particular morning was 'better' or more God-pleasing just because it was more skillfully performed. i know members of my own congregation who do not care to sing aloud or audibly for the very reasons i'm talking about.
Why? Why should these people ever get the impression that their sacrifice of praise isn't good enough for God's ears? or their brethren's ears? No, i don't think this practice is inherently sinful. But if this is a possible/probable result, then is it worth it? Is it worth the cost to create an environment where certain people feel their worship and edification is less valuable than others? --that God or His children don't just accept me as i am, but require that i show up with some natural aptitudes before my worship and edification is 'on par' with theirs?
i've been in a song service led by a man who was, frankly, a terrible musician (i teach music for a living, by the way). He was off-key and off-tempo. But judging by the expression on faces and the unified participation, the congregation was well led in worship to God despite being poorly led in correct pitches and rhythms. He certainly led me well. Why? i knew the guy pretty well; i knew his heart. And i could see from the expression on his face that he was after handing God his whole heart with unwavering enthusiasm. i can't fathom why that guy somehow pleased God less or edified his brethren less on account of his poor musicianship. Why shouldn't he be asked to lead singing again? Why should he have to sit down and let a better musician lead?