@contrapunctus @agturcz first of all, please don't explain centralization to me, I was talking about it before it was cool:
https://media.ccc.de/v/30C3_-_5319_-_en_-_saal_g_-_201312282330_-_technomonopolies_-_rysiek
Secondly, "some clients don't support X" is a deal breaker. Because now regular folks need to track and think about whether or not their contact's server supports a safety feature they rely on.
Third, "if someone sends a cleartext…" is not anywhere near being acceptable for a communication tool like that. Sending cleartext should not be *possible*.