4 dman on the ice is an anti-torpedo system. Though this is really just 2 D-man being converted to forward positions. Nothing's really going on with the system play. If it was, that would be really exciting.
It was used a bit in the 60's to counter the Torpedo system. Which was one of the last true examples of a coach playing around with the way people actually play the game, the other was the trap and the variations of that. I've had coaches who've employed the torpedo system and it worked really well (4 forwards and a D, though 2 of the forwards play more of a half-forward style) we were dominant because most teams couldn't handle the pressure.
Torpedo system - Wikipedia
I've often wondered why GM's and coaches don't look at different set ups on ice. There's nothing in the rule that says you have to have a 3-2 system. Rolling a 2-3, or 1-4, or 4-1 should be options, and I think it would make team identities and builds a lot more interesting. GM's should be exploiting the market, their pipeline, and scouting expertise and and building their teams accordingly. I'm sure the big issue is, most people don't want to experiment at that high of a level, people are too scared to be original when millions are on the line.