The need for hyperrigour is one thing, but I think that unfamiliarity with the literature and poor science communication comes in play as well. I'm a biologist, so I have access to the scientific literature. When the mask debate came up, I did a small literature review to see what the science said. I was surprised to find that the science was pretty nuanced and subject to debate. Some papers suggested that masks are ineffective,but others suggested that they could play a role. Many of these studies had strong limitations and only provided insight for very specific scenarios. For example, some papers treated infections as a binary (they either prevent infections or not, rather than looking at reducing infections), many papers looked at preventing the mask wearer from getting infected, but not at reducing the spread by infected mask wearers, etc.

Any scientist can tell you that it's hard to keep up with the literature, and it's very likely that many of them spoke out against make without reading the papers. I was taught as an undergrad that they don't work. Many of these things are passed down uncritically.

This issue demonstrates that we need to improve science communication. Many scientists and public health professionals declared outright that make don't work. This shows that they are either unfamiliarity with the totality of the literature or that they feel the need to give definitive statements. When some people provided evidence in favour of masks, some of them switched to saying that make are needed by medical professionals and that improper usage can increase your risk. A better approach would be to acknowledge that there is uncertainty at that in their view the evidence against masks outweighs that in favour. If they took this approach, it wouldn't seem like they just flip flopped when they started recommending make. Also, it's not hard to train people to use them, and condescending to treat people as being too stupid to wear them.