wots the point in pprune if somebody askes a question and you give a smart arse answer or tell them to go do a search
And what's the point to continually have to repeat yourself when the poster could just do a search or read the sticky which clearly states READ BEFORE YOU POST A QUESTION!?
I dont think it is fare to refuse anybody from any country a Visa with out a good reason.
To be honest, it doesn't matter what you think. The Americans are still a little bit upset about the whole "9/11 thing" and getting a flight training visa is not that easy. It's an expensive, intrusive and annoying paperwork process involving a visit to the US embassy and having your fingerprints taken among other stuff.
It's a big shame because America is an amazing place to fly around and a great place to gain flight experience but it's their country and they make the rules.
P.S. Fortunately you don't need a visa to fly there if you already have the licences but some countries citizens will still be required to have a visa to travel there. Afghanistan, unsurprisingly, is one of those countries.