Why baptism, why sacrament

Mosiah 26:22

For behold, this is my church; whosoever is baptized shall be baptized unto repentance.

That's why we get baptized. We don't get baptized to covenant to be perfect, we get baptized to covenant to repent when we aren't.

We don't take the sacrament each week to signify our perfection or even our repentance. We take the sacrament each week to signify our willingness to repent and try again.