Ahhh... This is what I love about electronics, fuel, and oil theories. Everyone has their theories and hate to be wrong! If you'll notice, I ended my last post with "do your research!" Because, as you said, stupid people think they know it all. Apparently for you, Red Line, Royal Purple, and CraneCams know more than Castrol, Mobil, and CompCams. The key word through this all is recommendation! These are all recommendations.
True synthetic, false synthetic, half synthetic, purple synthetic... I don't care what term you use, any and all oil can be used for a break-in if the proper procedure and any necessary additives are used. The fact is, there is no documented proof either way, and it may well be an urban myth when all is said and done.
Personally, I believe that if an engine is of the capabilities to even NEED synthetic oils then it will have been professionally built and, therefore, will not need the mythic "break-in" period. Ask John Force and his crew how many miles they run conventional oil through their motors before switching to synthetic. Ask Tony Stewart and his crew the same question. Mario Andretti or Sebastien Loeb.
Honestly this discussion is pointless. Unless you're racing, there is no need for synthetic.