Snowflake is for places where the tor network itself is blocked. You can uncensored internet with tor but if tor is blocked, you have to use some bridges to connect to tor network. But bridges needs to be configured and people who host bridges have some expense to keep it online. Snowflake is a temporary bridge which anyone can enable anytime and stop anytime. People who tries to connect through snowflake can easily connect automatically to any active snowflake proxies and also find a new snowflake proxy when current one goes offline.

Here is the official note about it