Why are clearly superior screenshots replaced with crappier ones?

[MoviePropMaster2008]

I've had High Def screenshots REPLACED (by other members) by identical shots that are clearly inferior screencaps on movie pages. Sure, the person completed the page because they had the DVD, but does it make sense to delete the super clear image and replace it with a bad one of the identical frame of film? I've been told before that this is done, because the superior quality screencaps makes the rest of the page look bad because the 'other member' is uploading lower quality images.... so the solution is to remove the high quality ones.

Do members buy this as a legitimate reason? Just curious.

I only ask because of the instances I am aware of, and those are of higher quality screenshots that I put up, being replaced by worse quality ones. It may have happened to others but I am not aware of any incidents, being that it would not catch my attention.