The Short Version
Judo does offer genuine self-defense utility in unarmed, one-on-one, close-quarters encounters — its throws and leverage-based techniques can neutralize larger opponents. However, the claim's unqualified framing omits critical limitations consistently acknowledged across sources: Judo training is gi-dependent, lacks a striking component, leaves practitioners vulnerable to punches and kicks, and performs poorly against multiple attackers or armed opponents. Even the most credible supporting source limits its endorsement to "certain street fight situations." The claim is partially true but misleadingly broad.