when running a community, the owner has to configure some anti spam options, like for example it could be a whitelist of him and his friends. if he wants an open community, it gets more complicated, you have to let unknown people post, but also not let unknown people spam, so one of the option is SMS confirmation. eventually we will add more options like social login, confirming ownership of a domain name you own, owning cryptocurrency, etc. it’s a work in progress, but this anti spam mechanism is completely optional and arbitrary, it’s something that each community owner can configure in any way they want.