Thank you for your question.
I can not tell you why your particular man is not able to confront you face to face. I would have to talk to him to find out.
The biggest thing is, that he is afraid.
Confronting someone with the truth, especially to tell them you know longer want them, is very hard and scary. It is easier to simply ignore phone calls and not respond to email.
This is not the healthy way, because you deserve to be told, and you also deserve to know why. It is not healthy for him, because any issues go unresolved, so there is no closure.
It isn't just with the men, it is also with women as well. Some women can not tell the man they are not wanted any longer.
It is more a statement about what happens with adults. Adults in general, have been shown to lie for each other even when they do not know one another; they will go along with each other's story.
The same thing is true of telling bad news, or news that will hurt someone. Adults, though not a mature thing to do, will generally sugar coat it or avoid it all together.
What I am concerned about for you, is if you really need to be with someone like this. It speaks to his character, don't you think?