My comment was referring to the retail LLC arrangement whereby a few partners pool money, get a clearing arrangement together and let their traders open retail accounts, but extend them intra-day leverage from the LLC's funds. Some hedgefunds do this too.
I know you look down on this arrangement and I'll say without hesitation that there are charlatans who can set up shop under this arrangement and operate in a less than upfront manner. Because they are not regulated like an SRO-member firm is they can set up quickly, with less cash and possibly get away with more. However, there are also very well run, well capitalized groups that operate under this arrangement too. You cannot paint them all with the same brush.
If you are going to go into business with someone (and by trading prop, that's essentially what you are doing) you should do the due diligence first. This means getting to know the principals involved, checking their reputations, talk to former and current traders, etc. Whether or not licensing is required to open an account is one, but not the only, thing to consider.
I have traded with nasd, phlx and non-member firms and have had good experiences with them all. The overriding factor for me is the firm's and it's principal's reputation in the industry. I currently keep a six figure account at one of these big bad retail LLC's and have no qualm's whatsoever about the safety of my capital.
Industry regulation is definitely one of the risks that's out there though. We've woken up to a whole new paradigm on more than one issue.