the talk page archive you linked to is not relevant as it concerns the inclusion of the quote not the use of the word famously indeed few things are banned on wikipedia but there are very clear guidelines why do you think they shouldn't apply here why do you think that this one single fact needs to be described in this subjective way if it was silly to describe the opera itself as famous then you must believe that a critic's opinion of it could be more famous and more widely described as famous than the opera itself that's clearly absurd