There's enough documented cases where we KNOW this is the case to think this is likely true for a very large proportion of them. Dick Francis is a major case in point; his wife wrote most of "his" books.
Maybe, or maybe she was the one to convince her husband to continue the charade because she didn't want to be in the limelight. Or maybe it was their publisher that forced it when they started out. Or maybe ... But that's all speculation. We don't know how their arrangement came to be, only that it was, and that it was not against her will. As such, I don't see any objective reason to villify her husband.