They used to make us do this with gloves on when we didn't/couldn't spar.
I guess its not just a strength thing but also developing good leverage in the clinch. Good ish for GGG this most likely helps him create a bit of space and not get frustrated if they try to smother his good boy power.
I like the wrestling part, I think more fighters need to incoperate that into their training. That right there would help against fighters that impose their physicality.