ICONOMI is a foreign entity so it qualifies for Exemption from US Securities Registration, eventhough it raises capital in the United States:
https://www.sec.gov/divisions/corpfin/internatl/foreign-private-issuers-overview.shtml#IVIV. Exemptions from Securities Act Registration Initial Distributions and Resales
"Foreign private issuers may raise capital in the United States through a registered offering of securities or through offerings that are exempt from the registration requirements." This is a quite complex area of law. What you quote does not mean that all offerings by foreign companies are exempt. Not even close.
"Offerings that are exempt" are typically those which are limited or private in nature. For the Iconomi ICO, any Tom, Dick, or Harry in the USA could buy ICN. So it doesn't meet a limited/private exemption.
Other exemptions require e.g. that there be no marketing efforts that could be reasonably calculated to reach the USA. Probably also a failure. (If they were going for exemption that required this they would have handled all marketing themselves, and not outsourced to uncontrollable bounty program.)
And
even if the ICO was properly exempt, resale on the open market in the USA may not be exempt.
The SEC explains this with a quote that directly applies to the current situation with not being listed on bittrex or poloniex.The registration requirement under Section 5 of the Securities Act generally applies on a transaction-by-transaction basis. As a result, securities sold initially pursuant to an exemption or safe harbor from registration may not then be resold unless either an exemption is available or the resale is then registered under the Securities Act. The availability of resale exemptions should be an important consideration to a foreign private issuer; it may not only affect the price and ability to initially place the issuers securities, but the availability of the issuers initial exemption or safe harbor as well.
i.e., Iconomi is having a hard time placing its securities on exchanges because it can't establish an exemption for resale transactions on those exchanges. Hence they need to do the SEC registration work.
indeed, Cryptocurrencies don't require registration within US borders. Regulation is done at the exchange level, and foreign securities are not required to register with the SEC, that is 100% up to the broker-dealer, and their responsibility. The only advantage of an SEC filing would be the ability to list on the NYSE. (looks easy but not, look at Gemini) NYSE is an exchange. American CRYPTO-exchanges can list whatever token they like, because it is their exchange, and their state to state rules.
The IRS has went out of their way to make unregistered Foreign Securities taxable since 1993 (See chapter 7 of IRS code.)