It's not a randomly picked pro... If the own fighter who is debated as the GOAT (GSP) says that to him there's no way JJ is not the best of all times... Khabib saying the same as well, but actually, putting Jon Jones and Fedor as tied #1s... The if the own ppl who could be argue to be goat status all say JJ is the goat, I just don't see much ground for it to be otherwise.
His fight vs DC was ruled a no contest. But that's it. That was the only fight that had not a clear winner. The others, were not. Still, JJ defeated everyone else he fought... 29 - 0 with more than 90% being in UFC and 17 title defenses + double champion... There's the doping controversy, but again, the only fight it was a no contest was DC II. Out of that, JJ was the youngest champion ever, defeated his belt 16 times in LHW and 17 times counting his last HW fight.
Ppl can look at different aspects for GOAT, which I respect. But purely in terms of accomplishments, dominance, consistency, breaking records and getting double champion (while no one has been able to be triple champion yet)... It just makes it clear, to me, that JJ is the most dominant fighter of all time and, in terms of dominance as a fighter in his 15 years career in the UFC... Yeah, he's the most dominant and all in all, best fighter to ever fight IMO. I'm not talking as a fan or anything, I'm being totally honest.