I remember a big thing going round the local congregations back in the 80s where we were told not to buy mushrooms because the fertiliser contained a blood by-product.
To be fair, in the late 70s, early 80s when I was growing up the blood doctrine made sense because it was pretty black and white. As medical technology advanced that's where the grey areas came in and all this hand wringing about what is acceptable, what isn't acceptable etc started.
It then got exacerbated by things like cell salvage, not least as you had congregations (Chichester local to me for example) buying machines for the local hospital and then some Witnesses saying it would be against their conscience to use one.
You had congregation elders essentially determining what would be right or wrong and therefore steering people to a choice that suited an increasingly watered down front to the medical profession. It's no wonder that most dubs just tick all the boxes and reason that if they can't be DF'ed for it then it's OK. Zero critical thinking.