As for your question there are ways to mitigate that type of problem, joining fee maybe?
I'd be okay with this feature if I got a 2FA alert that something 'big' was about to happen, and could approve/deny it in realtime when it happens.
please for the love of alan turing understand that trust happens iff there are reasonably-enforceable boundaries, and "oh we're friends, let's opt out of reasonable information-theoretic security primitives" is not a healthy or friendly behavioral pattern.
/ if your PKI is so obnoxiously difficult to set up correctly that people are inclined to skip the crypto altogether, please get help.
sorry for the grouchy tone, I'm just sick of hearing software engineers pretend that shoddy quality control issues and products riddled with security holes is somehow positive.