Agree - although we came upon this advice only recently, we wouldn’t have followed it had we heard it earlier. But if the idea is to stand out among many highly qualified candidates, this advice does make some sense - relative to more obscure pursuits, there’s probably a glut of classical musician applicants to top universities.
We weren’t led by that consideration - focusing on classical music has helped D22 in many ways (e.g., teamwork, discipline, persistence, eye for detail, etc.), created deeper bonds between family members (e.g., an “old school” FIL who became softer and more patient - according to my wife - as a result of the passion he and D22 shared in classical music, D22 and I going busking to raise money for charities), enabled us to be part of a close knit parent community, given us opportunities to travel to different countries, etc. As I said above, no regrets.