Rickson went on to say that in MMA you would only use about 30% of the BJJ you would learn in class.
This is so true. We do BJJ most of the time with a gi and I constantly see moves that wouldn't work in MMA simply because the techniques require a gi to be accomplished. If you ask me, this is why wrestling is typically the dominant discipline in MMA because wrestling is literally controlling the person rather than controlling the clothing on the person.
Plus, you see it in the amateurs that even brown belts in BJJ get KTFO, aren't good at takedowns, holding the positions, etc. I think a lot of that is because they train with a gi instead of gi-less grappling all the time.