It's completely useless to talk about "total amount of missed games" over several years. It's a typical argument to make a less injured player look better. What matters in that regard is how many close to full seasons, and therefore a chance to after season recognition and trophies, a player has. Forsberg had in total 5 seasons with more than 60 games played, while Sakic had 15 of those seasons. One would expect Sakic to have gathered a lot more hardware in all those chances to be regarded as good as Forsberg. It's also not sure if Forsbergs 60+ games seasons necessarily coincided with Forsbergs peaks. Noone will remember his 55 points in 37 games in the 2003-04 season even though he played the best hockey of his career IMO, and noone will know what he could have done in the 99-00 season, (right after his sensational 99 playoffs), when he missed first half a season due to injury. Nobody will talk about his 05-06 Flyers season when he led the league in points half way through and was widely regarded as the best player in the game when a mid season injury occured.
So you see, the disadvantage of his injuries is much bigger than you point out. Still he tops Sakic in career points per game 1.25 to 1.19 even without the era-adjusting of Sakic' first 6-7 years in a much higher scoring era.