My point was that if Marvel released something that was below par, say on the level of BvS, SS, or JL, I think we would see similar smaller numbers.
If Marvel started releasing movies that were perceived to be awful, that would certainly have an impact. However, the effect would probably be more immediate at the domestic box office than the international box office.
That tends to be the pattern for these franchises. It takes longer for franchises to catch on overseas, but it takes longer for them to fade away also.
The brand definitely helps first weekends, but quality movies are what give them their legs and their good box office revenues.
As a general rule, I think most would agree with the following, more or less:
Opening = hype + brand strength, Legs = quality and word of mouth
But there is also the cumulative effect of brand building over time, which seems to impact the domestic and overseas box office differently.
For example, in terms of tickets sold in the domestic market, the only Marvel Studios movies that have done more business than the first Iron Man (adjusted) are Avengers, Iron Man 3, Age of Ultron and Civil War. So basically the event movies that benefit directly either from Avengers, Iron Man, or both. Meanwhile, every movie Marvel studios releases does more business overseas than the first Iron Man.
Doctor Strange is a very well-received origin story, but it did only about 60% of Iron Man's business domestically. Overseas, the situation is roughly the opposite, with Iron Man having done only maybe 55-60% of Doctor Strange's international box office.
So quality is one factor, but not the only one.
Domestically, Iron Man was an event in a way that non-Avengers movies aren't anymore. Even if the movies are very, very good, like Homecoming and Ragnarok. Internationally, Marvel Studios has built its brand so that any release will do more business than its early movies. One very bad movie would not be enough to change that, though a series of bad movies would start to have an impact.
