cofty: In a modern abattoir the blood is collected and used for all manner of commercial uses. Therefore is would be unlawful to eat the meat you buy in a butcher's shop or supermarket.
When I was a kid, we were not allowed to eat processed meat. Bologna and hot dogs were seen as the devil's food. The only processed meat product that anybody in the congregation would buy came from a Jewish kosher meat processing company.
I have always had a suspicion that those earlier dietary rules were rooted in the financial alliances that the Bible Students had with the Jewish community - "tell your adherents not to eat blood and buy our food instead".
Where the WT really lost the plot, though, was when they banned the use of certain pet foods and garden fertilizers that were made with blood products. That was insanity at its finest.