atagar: I think they don't because for people with reasonable amounts of bandwidth, it's much better not to use accounting.
atagar: For example, I have a 3TB quota on a gigabit link. Now either I use accounting and don't limit my relay in any other way, meaning it will not run for a whole month, and when it runs, it will attract massive attention.
Or I limit it to 500kB/s, make it run as a stable guard, and don't come close saturating my pipe at any point during the month.
imnsho the latter is preferable.
of course, the worst I could possibly do is to use daily accounting, so that my relay will run for a bit of every day of the month, reducing its stability even more
If I, on the other hand, have a quota of 100GB/month, it makes perfect sense to use accounting to provide a reasonably fast (let's say 100kB/s) relay for a part of the month.