None of the guys you listed have been clinch technique than an mma who trains it every fight and is actually one of the most underrated aspects of the sport. Conor will man handle him in the clinch and toss him around
Clinching in boxing and MMA are entirely different things. In boxing it is usually used to get out of danger, even give a sort of rest, whereas in MMA it is extremely energy intensive, basically grappling on the feet while worrying about knees, transitions to the grounds, getting your feet stomped, and so forth. In boxing it can be fun to "man handle" the guy in the clinch but it has very little to do with winning the fight.