You give your first impression in anywhere with Your board Marks, For many it may be the criterion of Screening, Even in many private schools You can Join as a teacher if You have good score in calss12th, Having good marks on class12th is always a plus point and it will help You always to be stand out unique among the pool of People applying for a job, For instance consider Yourself as Applying for a job which has 100 vacancies and if total applicants are in  thousands so why would they are Goin top waste their time in taking the interview they may simply make some cutoff to shortlist.