I never understood insulting a guy because he's trying to learn your language.
That being said, I don't think you will find a serious clan which does not have a microphone requirement. If you think about it, this just makes sense; you need to be able to communicate instantly while performing other actions all at the same time. Typing/reading can get you killed in a clan match.
The chatter on VOIP during pub play is nothing like communication during a clan match, if that is what's turning you off. Also, most clans use TeamSpeak or another 3rd party product rather than the in-game VOIP.
Other clan benefits to having TS are the ease of communication during practice, ease of setting up scrims (we all know each other's TS channels), and ease of setting or changing server passwords for scrims and matches.
Without some sort of mic you can never fully participate.