Since the SEC (the USA's security regulatory and enforcement arm) determined that the DAO was a security , and thus subject to its regulations, there have been many ICOs that block Americans from participating in them. Since this has become common practice, I often come across people espousing such a procedure as a way of legitimizing ICOs. Although such efforts may seem to solve the issue at hand (operating ICOs outside of traditional securities laws and regulations), it is actually not the silver bullet ICO proponents are hoping it to be.
More here:
https://www.decentralized.tech/blogs/icos-banning-americans-the-not-so-silver-bulletOh well, this is bound to happen sooner or later because of bitcoins. And with all these Altcoins popping out everywhere? This just does nothing but irritate the banks and governments more and more each day. But even so, they can do nothing unless they ban the exchange sites or anything related to crypto currencies in their place. Because if not. People will still find a way to get to it. The temptation to earn without that much hassle is just so hard to resist for most of the people.