The idea behind this bot is that you want to take control on who can contact you.
Usually you use a public accessible username (@ handles) to be reachable without sharing your telephone number. This also means that strangers could talk to you and annoy you.
To prevent that, you could register a bot using https://t.me/BotFather and use this code to have actual contact requests.
To prevent that, you could register a bot using https://t.me/BotFather and use this code to have actual contact requests. Also you could then disable the username in telegram.