Ehhh I am with you that we should have solid training and mentorship, but I do think it makes sense to try to pull some attrition to the left. As an instructor, I was frustrated anytime a student was halfway through advanced and was like "eh, I don't like this anymore. I thought flying would be fun, but it's mostly just memorization and flying procedures."
I think with an IFS/NIFE/API whatever it is you can:
1. Weed out the academic non hackers. Some people just won't get the academics. Get them earlier rather than later... trickery on the tests isn't the answer, but we all know that guy who showed up to API and didn't study and thought "no one fails API, this will be a breeze," partied too much and was the TAD ENS fixing Page-2s six weeks later. This isn't fixed by mentorship: these students already had every instructor tell them to study in groups, their buddies offering them to join in, and some sort of review board to try to address their problems.
2. Make students realize how much memorization there is ahead (again, don't be ridiculous, but memorizing a few limits, EPs, and procedures to give them a taste of what Primary and Advanced will be like) so you weed out the people who thought flying would be kick the tires, light the fires, and take to the open skies and max throttle. I imagine most of us thought it would be like that but at some point we all bought into the safety our procedures brought us and we all realized at some point that some airspace is friggin crowded and we need to be procedurally compliant. There are a good number of students every year who just don't want to mature to that stage, and when it smacks them in the face, they don't think flying is fun anymore and don't want to do it. Get this to them earlier.
3. There are a good number of people who just get airsick. Sure, give them the puke-chair a few times, get them acclimated, but some people it just turns out, physically either don't like flying or can't acclimate to it. Get them out of the program in a $100/hour Cessna instead of a however-many-dollars per hour T-6.