I’m not sure how you come to your conclusions; I’m not being defensive, but just pointing out the obvious - you would prefer a “clean” feed rather than help ensure Monzo users who may not be as money savvy as yourself. That is selfish by definition: “concerned chiefly with one’s own personal profit or pleasure”.
Do you agree that Monzo is customer-centric, or at least should strive to be?
Do you agree that part of customer centricity is alerting users of active scams in a timely manner e.g. Ticketmaster database breach?
If you answer “yes” to the above, then why are you saying Monzo should not use the most timely, direct way to alert users of active fraud scams?
Regardless of whether the user is or is not aware of fraud, and regardless of the method of communicating the scam, for users the worst outcome is minor annoyance, the best outcome is someone avoiding being scammed. The trade-off seems clear for a customer-centric bank.