Nowhere in the article do they claim that it's THE factor, just a key factor in combination with "habitat loss, chemical pollution, invasive species, and climate change" (3rd paragraph).
I think that's exactly how contemporary disinformation campaigns work. Say its almost totally pesticides, the win for them is muddling it into 'numerous causes.' There's so much money involved in some of these issues that stakeholders can spend millions (billions if you own fossil fuel reserves) just to move the needle slightly.
Yeah usually 80 percent of any problem is just one factor. In this case that's clearly pesticides and the discussion of more potential causes is a benefit to the producers.
This is exactly how it played out in the popular perception of climate change.
>“We strongly believe artificial light at night – in combination with habitat loss, chemical pollution, invasive species, and climate change – is driving insect declines,” the scientists concluded after assessing more than 150 studies. “We posit here that artificial light at night is another important – but often overlooked – bringer of the insect apocalypse.”
That’s how most of this nonsense works. You just have to sow doubt.