This instance is from https://www.inverse.com/mind-body/male-female-body-evolution, but I don’t want to pick on that instance in particular. I see this stuff all the time in contemporary writing[1]. You want your prose to be “punchy”, even “hard-hitting”, so you choose words like “irrefutably debunked”, but you don’t want to be caught saying something that turns out not to be accurate, so you add a weasel word like “may”. I suppose “may have cast some doubt on that idea” just doesn’t have quite the same “zing”.
[1] On the World Wide Web, which is (just about (weasel words)) the only stuff I read any more.