Yeah, I've seen a franchise player on the Leafs in my lifetime (Mats). But I think the closest we've come to seeing a "generational" talent was Dougie, and that was only really 2 years at that level. Even then though, as great as those seasons were, he finished 7th and 4th in scoring respectively, and there was a comfortable gap between Dougie and the ridiculously elite players of that era (Gretz, Lemieux). Matthews has the ability to be just a hair below a generational level player imo. Basically super prime Dougie level, but every year for the next 10+ instead of just two of them. Loved Mats, but there is a big gap between how good Mats was, and how good Matthews already is at barely 21 yrs old.
I think it's a valuable exercise, when determining how good players across eras were compared to current day, to look at how much better the absolute best are than the player you're looking at. Matthews is neck and neck with the best players of this era offensively. Anyone else we would put forward for best Leaf was a pretty large step down from the best in their era.