Not sure if you're serious here:
I would like a tool for party leaders to better set up farm parties.
No! You will not have a tool for party leaders to set up proper parties! It is the job of the party leader to set up proper parties!
As to your last question, it has been answered many a time in this thread.
1. It will mean you have some idea of how the content is played at the very least.
2. One of the main reasons was to set up a farm party. To prevent those who join for the clear and leave after one run causing the party to fall apart, from ruining the party. Or is this a bad thing? tbh, this kills PF far more than not having the option does.
3. Also, it is not a 100% promise of totally skilled players, but you are more likely to get one with it. If you think they should only be implementing things that have a 100% success rates, you are being foolish, as this is nearly impossible.
Umm. I'm going to assume you were someone who read the thread title and nothing else. But yeah.... Isn't finding your own group what PF is for?