I agree some identities are much worse and there are some that are just in the eye of the beholder based on values (e.g., being goth v. being an elite soccer player). I agree there's an argument that having more well rounded children might be better off for society too.
However, this runs into the 1000 touches problem (that people, whether its the violin, soccer, or math, get proficient by constant repetition in the 1 thing). Everything for kids (whether it's grades, violin, equestrian, dance, sport or even fake charities kids applying to fancy private schools feel compelled to start) is in this arms race to build expertise, because the kids want to stand out when it comes to college admissions. Add the propensity for kids in high school to want to chose a hat to wear, and a healthy dose of parental pushing, and it's the perfect storm for an arms race. The reality is someone doing 3 or 4 on the list probably won't have the chops to get a look at higher level soccer team, play on the competitive jazz band, travel with the debate club, run the student council, and maintain the grade point average they need for whatever college they are aiming for (which as we've discussed elsewhere on these forums, matters even for soccer players since grades play a role even in recruited admissions and not all scholarships are pure sports scholarships due to the various caps).