You must have missed the missile of a right hand that Canelo landed FLUSH on GGG yet he marched on unfazed!
I don't think any human alive could take a flush series of Jackson punches. Very few withstood even one. Golovkin's chin is very good but he does look affected at times, evidenced more by his body language than anything else. I wouldn't pick him to remain standing against Jackson providing Jackson caught him clean. Could well beat him though. In fact I reckon he does.
Define "elite". If one were to build a top 10 list of the hardest middleweight punchers over the last 20 years, I don't think it's possible for Lemieux and Jacobs to miss the cut. That would register as "elite" to me given the number of middleweight fighters in that time span. A-class punchers haven't fazed him. Neither have the punchers a half or whole grade behind that. While it's possible an all-time level, S-class puncher like Jackson might reveal the limits of it, it seems a little presumptuous to assume it'll crack the first time he gets hit with something harder than he's already been hit with. I'd rather give the benefit of the 35 year old guy who's never been knocked down or seriously stunned as an amateur or pro despite fighting his share of punchers with a pressure style.
Welp, sounds like Canelos stock has dropped around here significantly. Seems like mainly because people are threatened by Golovkins position in the all time rankings. Canelo might have average-ish power, but he sure as hell isn't an average puncher! He still couldn't do too much to the straight up, come forward Golovkin. It's interesting that some people think Canelo's punch was the hardest of the night, only because it looked aesthetically the cleanest. It barely moved him back. Look at the overhand Golovkin lands on Canelo, he crashed into the ropes looking like the leaning tower of Piza.