Here's my take. I lost 20 pounds on WW. Yes, the 18-23 range is tough, but you can make some very good choices with it. If you do cardio, it can boost up your points by one for every 100 calories burned. If she insists on doing WW, send her this link.
http://healthdiscovery.net/
It's a discussion board, called bootcamp buddies, for the die hard weight watchers. It is very helpful and everything that you asked in your question is covered by this board.
Now, there is another spin to this as well. Two ladies who were doing WW's and who worked out noticed that the more they worked out, the slower they lost weight. So they developed their own plans based around weight watchers.
One is called the wendy plan, and one is called the C.J. Plan.
The CJ plan is for people who really, really work out. It gives you plenty of points to play with, but you have to earn them, hence it forces you to work out.
Some people need structure in order to lose weight. I did. I went from WW's to feeling completely loss to doing CKD. I am one of the ones who needs a map. For me everything has to be black and white.
Anyway, get her on that board if she wants to stick with WW's. A true WW knows that you need a balanced diet. Yes, you get 18-23 points but you should use those points for lots of protein and other good things that your body needs. The ladies on that board know their stuff and they will help her out. Then when she's graduated, like me, send her here!
Wish her luck!