This discussion always drives me nuts. In my opinion, the best way to look at how great Gretzky was, or any other player, is to compare him to other players of his time. Yes, Gretzky played in an offensive era, but he also outscored everyone by 50% most of the time. There has never been another player who has done that. Not even close.
Those people that say Gretzky would never score 50 pts in todays game forget the equipment, training, travel, nutrition advances that have been made and how they benefit players today. He was too slow? skates and equipment are faster and lighter now,. Shot not hard enough?, try using that crappy Titan stick compared to todays sticks. Not big enough or strong enough?, players back then barely worked out, so if he played today, you can bet he would be bigger, stronger and faster.
If you never saw Gretzky play, you truly cannot appreciate the vision he had on the ice.
It's hard to compare era's, but again, if it was so easy to score 200 points per season in the 80's, how come nobody else did?