Jiu-jitsu's core goal is survival. Jiu-jitsu is more than just beating your opponent or learning proper technique. It is a form self-defense that teaches practitioners how survive a fight, regardless of whether it is in MMA or street fighting.
What are the Weaknesses in Brazilian Jiu-Jitsu 2.1. There is little to no stand-up practice. 2.2. Multiple Fighters. 2.3. High injury rate. 2.4. BJJ Off The Mat. 2.5. BJJ is a practice that uses concussion.
BJJJ is not violent. It's actually quite the contrary. It is difficult. It will teach you the discipline required to excel at your chosen field.