Well, this is debatable because I know for a fact that for degrees like engineering, medicine and veterinary medicine they look for teamwork and leadership skills. Regardless, how can doing extracurriculars hurt your chances??? If all you’re doing in sixth form is studying, then you aren’t going to have a happy time at an academically challenging university.
If you do extracurriculars and are committed to them, it shows that you are disciplined and committed and can balance a healthy lifestyle.
Look, maybe they don’t say that they care, but you can build on many skills by having an extracurricular, and your interviewer will possibly see those skills.