What does weight of line versus tape have to do with backing?
Most people use mono for backing with braid. Reels are designed to be fully spooled (or almost) for best performance. Because braid is smaller diameter and much more expensive than mono, it takes a lot more line and $ to fill a reel to capacity with braid. In this regard, I understand why folks use it as backing for braid. Plus, if tied properly, mono will not slip on your spool and braid will.
I think that most folks who fish braid use it for specialized applications like pitching in heavy cover, etc. Full spools aren't needed in these presentations.
Myself, when fishing for BIG fish, I want my spool full of braid to allow for multiple reties during the day. This is why I only use tape for my backing. Keeps the line from slipping on the spool. All the other talk about "cushioning" is just that.
"Things turn out best for those who make the best of the way things turn out" - Zachary Troy Schrah - a young man with vision far beyond his years.