There are 2 restrictions:
1) Points of evil... If an ip is associated with (for example) spammers, points of evil are attached to the ip(range???). If you want to create a new account from a device with an ip that has units of evil, you'll have to pay a small fee in order to activate your account
Probably it's this reason.
I knew people, from different countries who experienced similar, some were demotivated for joining, but others just payed, the fee is small.
I think it's ok, if you consider your participation in forum seriously - why not to pay.
And if you take part in bounties, 1 or 2 bounties can pay more than this small fee