I agree that the artist bears the responsibility for the thumbnail they upload, but I contend that most thumbnail violations are not willful violations but innocent misundertandings of the policy.  My experience was such.  I still believe that my original thumbnail (see earlier in the thread) was in compliance.  

So, instead of focusing your enforcement technique on the thumbnail itself, you seem to prefer an enforcement policy that is more akin to punishment.  I have made suggestions on ways to enforce without such punishment, but you do not seem interested in pursuing them.  Instead, you point to the 99% compliance as support for your technique.

Note, as always, I do not question your comittment to the smooth operations of the site and to the implicit support of artists that results.  I just feel that in this case you are choosing heavy-handed enforcement when it is not necessary, and it is engendering ill-will needlessly.  

At this point in the discussion, I feel we're rehashing the same issues, so I intend to take a break from it for a week or two.  I only ask that in the meantime you do give my suggestions some thought.

Dan among Den