The rule that only accredited investors, which means people who are already wealthy, are allowed to participate in certain ICOs is senseless imo. It's like saying "YOU'RE NOT WEALTHY YET, SO YOU'RE NOT ALLOWED TO BE WEALTHY." Stupid society, with obsolete rules, we're living in.
Disclaimer: I'm not a US citizen, and I've not read that law
I think mostly this may happen because ICOs may be somewhat banned in those countries so they may do a private sale to sell their tokens(Some are not even allowed to mention ICO in their sales but token sales may rather be accepted). Some also need some minimum requirements to invest while others may be looking at big tech firms because of the nature of their project.