Responsa sur Les Proverbes 14:37

They responded: Even though Kiddush is only recited in the place where a meal is eaten (Pesachim 101a:3), it is nonetheless a commandment to recite Kiddush and Havdala in the synagogue. For "in the multitude is the glory of the King" (Proverbs 14:28). Moreover, Channukah candles are also lit in the synagogue, even though each person lights in their own home. So too, there are some people who don't know how to recite Kiddush and Havdalah, and when they hear it in the synagogue, they are encouraged and learn it, and later recite it at home.