I'm an expert too, and I've studied for decades too, but what you mean is you'll stick with people who tell you what you want to hear.
What exactly is it you think you've heard, the thing you're referring to when you say there's "no bias reason". Is it that there's something in animals you need? If so, which other experts told you this? Can you point me to a study or essay they've done on the topic.
I wonder how they account for the millions of people who never use anything that involved animals in any way, some right fro the moment of conception, like my 20 month old son? So far, he's healthier and smarter and happier than most other babies the same age, so it doesn't seem to be doing him any harm yet. Do you really think there's something in animals he needs? And you need? And I need? Well I haven't had any of it (whatever it is) in several years now. Same with my wife. And same with dozens of people I know. And same with the human species at various points in our evolution. We CAN digest other animals, but we sure don't need to.
But please, point me to the evidence brought forth by your experts. The ones you believe without investigating, and base major life decisions on.