What gives this person's post away as false is that the guys he/she supposedly trains with are not wearing protective cups. Every man in the striking sports wears one. If they didn't, they'd quickly start once they were struck there. In my experience, some BJJ guys didn't wear them due to having a hard plastic cup between their legs that prevented them from doing their guard. With the new models featuring softer sides, that doesn't seem to be a problem.
I once sparred with a black fellow and, I was clearly outclassed in the boxing dept. I Where I outclassed him was in grappling. I made three good takedowns after we got into a clinch. All of them resulted with me being in side mount, or top mount. What was the difference? He grew up fighting with his fists, which gave him the advantage. He was also tall and, lean, with good reach and, fast reflexes. I wasn't as fast, or as tall, but I had over 10 years experience in folkstyle wrestling and, 3 years of BJJ. I probably was a better grappler than he was a striker.