Crysta sadly hasn't been approved by government authorities in some countries (like Australia), regardless of how you want to pay for it, so it's not even listed as a payment option for those players who are unfortunate enough to be in those countries.

This was the issue I faced back when 1.0 was first released - I had no choice but to use Clicknbuy, which I had issues signing up with as well (my debit card didn't have Verified by Visa on it at the time, and took me ages to sort out).

Most banks nowadays offer Visa or Mastercard debit cards as a feature on their accounts so it's not too hard to get one, it might just take time to get the card set up, and require more effort than a lot of players are willing to expend just to play a game.