From personal experience and I think you yourself have stated this people don't say what they haven't liked to creators at cons. If you don't go by the internet how do you know why someone dropped a book?
It doesn’t really matter why any one person dropped a book–there are a million possible reasons. What matters is what the audience does as a whole.
Seems like some people fail to understand that this is a numbers game. No matter what there will almost always be people dropping a book for any number of reasons. As long as the book can attract new readers to sustain itself (and preferably expand and grow the readership) then that's in order.
If the book needs to be cancelled it could probably be well worth spending a little effort in analyzing why and I'd imagine that Marvel would use 'Internet chatter' as part of such an analysis. Part of.
