Originally, a 5th star was coveted. There were very few and the ones that got a 5th star were mostly exactly that, and panned out like so. At that time there was one high school all-star game that counted and predominantly that group was your only 5 stars.
Translation: 5 star was rare = black marble in a bag of predominantly red marbles = low probability of pulling a black marble; low probability of getting a 5*.
Now, there are way too many 5*; more than there should be. There's a second all-star game with additional 5* kids + additional elite camps. So, let's say double the number of 5* these days.
Translation: Oversaturated. More 5* issued now than ever and the list has grown compared to a number of years go. More competitions mean more kids getting an "elite" status that shouldn't, because $ drives it. Similar to Special Forces in the military it was once a truly elite group. Now there are thousands or so, not 20 or 30; not that many people are that special and not that many players are really a 5*. Hense, why you see more bust, because they never were 5* quality = Oversaturated.
"More competitions", "more opinions" --- You stated my case for me. More = Oversaturated. Once you reach the tipping point there are too many --- oversaturated.
Which leads to my last point - law of diminishing returns. Once you get to a point of saturation (too much). Adding an additional item, in this case, a 5th star adds little to no return on investment.
Translation: because there are more (I believe too many) 5* given, schools pick up coveted 5* (who aren't) and get little to no return and end up having a higher number of "bust". ND has certainly had an issue with this.