As Micheal says: (But I see nothing biblical about it) The male musicians had a fairly limited choice ("quite narrow boundaries") of what they could wear when performing, and those narrow limits to their choice are because of what their audiences expect them to wear. They are saying that audiences have expectations of fashion for males that are quite narrow, not flexible, not broad, quite restricted. So, if men on stage have wildly unusual fashion, audiences will react badly. By contrast women were accepted with a much wider range of fashions.

Thank you Michael

This appears to be about fashion and clothes choices made by popular musicians. So, "strayed away" from, here, means "move away" from, though "stray" has overtones of sinning, from the Bible. "Quite narrow boundaries" - "quite" just modifies "narrow", makes it a little softer. In series : he's small, he's quite small, he's quite big, he's very big. Narrow = small width. Boundaries = things that mark the edge of something, sometimes things that should not be crossed. The male musicians had a fairly limited choice ("quite narrow boundaries") of what they could wear when performing, and those narrow limits to their choice are because of what their audiences expect them to wear.