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
I'm very happy that you commented and I want to thank you for taking the time to read it. I will read the link you provided carefully to see what it contains. And my purpose in doing this is that I don't want anyone to receive fake user hive from me, meaning that someone uses multiple accounts with one user.
Maybe you're right, I'll think about it.
During the account creation process, the user either pays for their account to be created or they use a free service provided by someone else who makes verifications before creating the account. So it's the responsibility of whoever is creating the blockchain account: https://signup.hive.io/
And one person using multiple accounts is perfectly fine. There are other things which are problematic, such as abusing the reward pool, and there are groups that watch for that and intervene when necessary.
Feel free to ask questions, you'll find a lot of help around. :)