fighting off back leg question

[shs101]

A basic tool in boxing is to keep your weight equally distributed and back foot UP. Ive seen an interesting post on old school concepts about fighter actually keeping their back foot planted to actually get more power in their punches and to compromise balance at all times, seem interesting.....In Broners last fight w/ Gavin he had he back heel planted a decent amount in the fight, thats just a quick example...
My question is what are the benefits to this? Any other modern days fighters successfully fight like this?

[sugar555]

You get more power out of the punches that come out of your rear hand or right/left which ever style you are but i think it reduces mobility i sometimes do this because my coach says learning how to can benifit me but its something alot of boxers dont seem to use anymore equal weight distribution is ideal but if your looking to land a hard straight right or left i guess planting your back foot would be good.