The obvious question is whether that actually matters all that much for securities, since the broker/exchange adds negligible risk and overhead for the buyer relative to the trust in the public company needed to buy a stake in it and the costs of meeting regulatory requirements for public companies.

Anybody who's more worried by the potential complications of T+2 settlement when purchasing blue chip stocks than the Wild West world of ICOs shouldn't be investing.

And you can maintain custody, so somebody isn't loaning out your shares.

There's a 95% accurate O(1) solution to determine if an ICO transaction has integrity.