The usual RACA word is to call people SECTARIAN if they will not use musical instruments NOR will they cease teaching what they and all of history says about the nature of the Church which has no role and no dole for musical or theatrical performers: Jesus called them hypocrites? Who? Why the Scribes and Pharisees who changed the "Bible" to avoid having to teach the Word of God. Their motive was so vile it could never happen in a civilized society. NO? What did they do? they made long prayers to justify picking the pocket of the Widows and hones working people NEVER asked to tithe. Christ named speakers, singers and instrument players who performed for pay to the audience so marked as refusing to do what Christ through the prophets (only) taught.
A heretic or sectarian is the one who would impose something as a "law" or practice on other people for which there is no command, example or inference and CONTRARY to many, many use of instruments as the MARK of people who refuse to preach the songs and sermons of Christ in the prophets and prophecies made more perfect and left, like the prophets, in a written example for us.
I Corinthians 5 sets up those who must be warned against and 1 Corinthians 6 fully identified those EXCLUDED as the same slick speakers, singers and instruments, then and now marked as effeminate hypocrites
I don't think they are too dumb to misunderstand: they just know that you cannot get rich and famous on preaching the Word as it has been once delivered. Anyone who thinks they can fill in the BLANKS with their own imagination SHOULD tell those with eyes and ears that the blind is leading the blind into the ditch: the ditch is defined as the pit into which the Babylonish kings/queens will be cast alive into the lake of fire along with their machines.