9", 10" or 12" tonearm?

Can anyone explain why many analog aficionados like or dislike 12" tonearms? What is the main sonic difference between a 9 or 10" tonearm and a 12" one? Is the 12" dogma outdated? I must say that in the past there were more 12" designs (SME 3012, SAEC, Audiocraft) than nowardays. Is 12" for "audiophools" with strong nostalgic feelings (like me)? (Especially when combined with those old Denon 103 or Ortofon SPU).