In my opinion based upon very limited data, I believe that the design of a SharePoint environment does not take backup into consideration at all.
In order to backup a SharePoint farm using the file list that I mentioned in the starting post of this thread, you will be limited by the bandwith of the media server responsible for that SharePoint backup policy. For example, let's assume you can get 200GB/hr of throughput (70MB/sec *3600 = approx. 200GB/hr..well, it's more than that, but I'm rounding down here). That's about 2TB in 10 hours, so you'd need a weekend to backup a 10TB farm.
So, if you have a farm with some multiple of 10TB of content data (20TB, 30TB, etc)....how do you do a full-farm backup?