I've no intention of getting involved in this slanging match here but would like to address the original question.

I think personal and private lives are important IF a songwriter or any other person advocates or "preaches"(as is often the case) some other mode of behaviour or is suggesting that the listener takes a certain path.

Of course, a songwriter might also compose a song to illustrate the standpoint or experiences of other people apart from his or herself which is maybe a trickier scenario. However, there is often still a message or moral in there somewhere which is intended to be conveyed to the listener. So, that shouldn't really be at odds with the writer's own behaviour.

As for not listening to songs or music by certain individuals, I agree that if the finished product in itself is good and apparently worthwhile then there's no need for it to be rejected.
After all, we all consume and use products and services on a daily basis where dubious and unsavoury people are often involved in the process or preparation.
e.g.. We don't always know who is working in the kitchen of restaurant, serving behind the counters of shops, delivering food and other mecrchandise to shops and so on. There's any number of examples.