Telling someone else how to do their job is rude.
Dave went to work and saw his coworkers screwing up.
Dave wants the team to get thier work done.
Dave offers his advice as suggestions to the supervisor.
Dave goes around telling everyone what they are doing wrong.
The supervisor notes that while most of them don't help, a few of them do and implements them.
Dave's coworkers all start telling Dave what he's doing wrong too.