I disagree lol.

This is conflating science and expertise, but it's probably still closer to valid than only "disagree without evidence". A person with no background on the area of interest (or science in general) is likely not to even understand what constitutes evidence of a claim. The set of non scientist people who can produce a reliable body of evidence disproving a theory that has not been found by experts in the same field is likely so small as to be negligible compared to the set of non scientist people with "evidence" from Facebook/other who are in fact just wrong.