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.  200.83.101.199