This is a very interesting article, so check it out. But I am most intrigued by this quote:
Marvel sells reprints of back issues. However, Marvel Time undermines and devalues the best stories. As Jerome Thomas wrote, “"I wonder how ‘One More Day’ impacted the sales of the many popular married Spider-Man stories that are still available in reprint? Stories like 'Kraven’s Last Hunt’ are now 'wrong.’ … One of the most touching issues of Amazing Spider-Man ever written was the Death of Aunt May issue. Marvel proceeded to crap all over that story by revealing that it was a really a genetically modified actress hired by the green goblin to blablabla and the real Aunt May was alive and well. Had Marvel not chickened out and kept Aunt May dead like they should have done, I think that a Death of Aunt May trade paperback could have been a nice little seller for decades to come.”
Marvel will of course reply that old comics don’t sell so well.. except for the 1960s stuff. And why does that sell? Because of a feedback loop. Readers constantly hear about those stories, so they have to buy them. Imagine if every great story was canon, and remained so. Everything would be connected. (And because death would be permanent, the back story would never become too complicated.) Over the years a reader would become aware of more and more connections between new and old stories, until every major story became a “must have” just like the 1960s stuff.
Connections between comics form a positive feedback loop for sales. Marvel Time destroys those connections.