This doesn't actually make sense, you know. Particularly the second sentence.Because it is also impossible to really know if 4e is going strong and yet people say so. Marketing is a reality that comes to fill the gaps of knowledge. But if one does marketing expect some people to question and rightly so. In the end this is how democracy works too.
What I see in this forum is a sort of denialism-lite. Its the same basic system whether you're denying the sales figures of an RPG you don't like, or denying the efficacy of vaccinations:
1. Demand absolute, 100% guaranteed, irrefutable proof.
2. When this isn't provided, because you've demanded an unattainable degree of certainty, proclaim that this means that the matter is an open question.
3. Throw out insinuations to get people to believe that if the matter is an open question, they should lean towards assuming that your side is the safest bet.
So on one hand we have best seller lists, print runs being sold out, reordered, and sold out again, we have the statements of people in the industry with direct knowledge, we have the statements of people in the industry with professional experience examining these questions and making business decisions based on them, and so on.
On the other hand we have quibbles about how complete these pieces of evidence really are, and a few people's personal testimony about their friends and neighbors.
Its the tricks and tactics of denialism that serve to turn this into a debate instead of a functionally closed question. The best seller lists are pointed out as not infallible. The fact that print runs sell out is used to argue that the print runs must have been too small and somehow therefore indicates a lack of confidence. The people in the industry are accused of being shills, or insinuations about a lack of candor, without any specific accusation, are used to muddy their reputations.
The goal is to make everyone believe that anything at all could be true, but that the people saying 4e is doing well are somehow sinister and not to be trusted, and that therefore we should presume that its doing poorly.
Just the same as any other denialism. There are some interesting scholarly articles about the phenomenon out there, if you care to look around. I'm not sure I should post them here, some people might read them like a manual.