I'm not sure if the microphone icons in Artist View is a bug or by design, and also I'm not sure if Apple really knows or cares about it.
It is ugly as sin and they better find a way to correct it. As far as I can tell, it has nothing to do with music being purchased from iTunes or being ripped from CD or else. I have an Artist Icon visible on some of my iTunes purchased albums but not on some of the other iTunes purchased ones. I cannot find a logical pattern why it is visible on some and not on all of them. In fact some of the ripped from CD albums shows an Artist Icon yet some of the ones purchased from iTunes does not. To make matters more complicated, some of the Artist Icons invisible in iTunes are visible on my synced iPhone running IOS 10. Bizarre!
All I see is a consistent degradation in Apple's software. Each new version usually takes away features and it is less pleasant to use. iTunes, iMovie, Airport Utility, iPhoto vs Photos, and the new Disk Utility to name a few. Apple is becoming the Microsoft of the past decade.