It used to be that a golf course would have tees at 5,500 yards, 6,000 yards, and 6,500 yards. Right?
Now you build a golf course that's 7,000 yards, and we realize that 5,000 is great for a lot of women/juniors/new players. And you still don't want more than a 500 yard gap between each set. So that works out to five sets of tees.
This doesn't mean that you need 5 separate tee boxes on every hole, but the idea of having 5 sets on the scorecard doesn't seem illogical.
BTW, I really like what Poppy Hills does: the back tees aren't even on the regular scorecard, and the names of the tees make one think that the 6,500 yard set are actually all the way back. If you want to play from 7,000, you have to know those tees exist and ask the starter for the scorecard specifically.