What we're talking about here isn't "a popular and comforting narrative," it's a description of a plausible model involving mechanisms that are at least partial

What we're talking about here isn't "a popular and comforting narrative," it's a description of a plausible model involving mechanisms that are at least partially understood. Once you're at that point, whether a challenge to that model or the model itself constitutes a claim that bears the greater burden of proof isn't as clear as it might be for any arbitrary claim.