To summarise: back when he was founding judo, Jigoro Kano removed the so-called ‘deadly’ techniques in order to enable live rolling, which had the end result of considerably increasing efficacy: because those early judoka could train ‘non-deadly’ (in the sense that you don’t have to fully crank an armbar, lock on a choke etc, as your opponent has the option of tapping before serious damage) techniques full-contact, they became highly proficient, and in fact more ‘deadly’ than their non-sparring contemporaries in ‘self-defence’ orientated styles.

Unless the self-defence stuff is ever trained with live rolling? Which I guess would mean people throwing punches full force to your face etc? I’ve never done much of it, as fortunately for me, RGA doesn’t do the whole “the guy grabs your jacket, you twist his arm up” or whatever ‘self defence’ type stuff very often. But I get the impression that live rolling isn’t the case with the self-defence part of BJJ, so its always restricted to drilling, and therefore much less useful than the ‘sport’ side of training.

The only way I could see ‘self defence’ training being useful is if it was effectively trained in the same way as the ‘sport’ side, which kinda blurs the distinction. I.e, the typical “guy tries to punch you” self defence scenario would involve one guy wearing gloves trying to knock you out, rather than just someone placing their arm there for you to fiddle around with in a non-live setting. So you’d basically be doing an MMA class.