Hi. There is no rule on Hive that only verified users can use it. People do create multiple accounts and run bots and that can be totally fine, depending on what exactly they do.

Making a face verification system sounds very sketchy. I imagine your purpose is to prevent fake accounts from entering your community. There is no rule on Hive that says this is necessary. It's up to you who you want to accept into the community. You can use other approaches such as interacting with a person for some time before adding them as a member to the community. Also, people can subscribe to the community, they can read the content and comment without being full members. Check this spec for more info, hope it's helpful: https://gitlab.syncad.com/hive/hivemind/-/blob/master/docs/communities.md