Could maybe wearing a sock help to protect against these risks? IE wear a thick sock and spray the socks (instead of feet) with the flex seal and you have less cancer/allergies?
Maybe if they took the brand out of it, it would be a good idea. I went through a Vibram phase a decade or so ago. I really enjoyed it; being unable to wear them at work, and the added difficulty of putting them on and off eventually turned me off to them, but I felt the concept was great.
For me the worst part was wearing them on any hard flat surfaces always made my feet hurt, I have a high arch and it felt like the pain was due to not having enough support
Not to mention trench foot and the wide variety of other diseases this would encourage. Shoes are breathable four a reason. This just feels like owning nothing and being happy about it, but shoes.