[andsoitis]

You can require address as part of credit card validation.

[midoridensha]

So only people with credit cards are allowed to use the forum? That shuts out a lot of people, especially in places where credit cards aren't used.

[andsoitis]

You’re right that credit cards are not a universal MOP (method of payment). Other options include debit cards, or systems like iDEAL, PayPal, etc.

[midoridensha]

Right, and those completely vary from country to country. Trying to get one website to support the common authenticated payment systems worldwide is basically impossible unless that website is Google.com.