There’s plenty of money and plenty of ideological conviction to produce negative papers on animal products. It’s not like it’s a hard battle of numbers where the winner takes all in the battle for public opinion.
We have only just now reached the point where the last group of anti-climate people have begun accepting that climate change is real. They've simply moved their argument to "it wasn't humans' fault". This is 100% because of the overwhelming influence of energy sector finances vs environmentalists.
The same goes on with food/animal topics.
Sure, the odd paper comes out showing that something bad is actually bad. But as HN talks about quite often, being a researcher is a difficult balance between producing research that pleases the financial backers and which is of real scientific value.