IMO, a martial art is considered self defense when it contains techniques/methods to defend against:
1. Multiple attackers
2. Weapons; gun,knife, stick/bat, sword ,etc.
3. Fighting in areas other than a ring.(e.g. small space such as closet, elevator,car,-dangerous areas such as rooftops and stairwells.
4. Training focuses on self defense, not ring bouts, therefore, tapping out is not recognized as submission.
5. Sparring/randori is not limited to one's weightclass.
I'm sure this list could go on, but I think you get my point.