Why is it that the changes in the formulation only have a negative affect on power steering systems and not on transmissions?

Has MB ever issued a Service Bulletin, etc., which addresses this issue?

I also use Amsoil atf. It's way thinner than p.s. fluid as far as I have noticed but I have had no issues whatsoever. I really don't think it matters what you use. I just chose atf because it seems to me that it would be better in cold weather since it is thinner.