How?
> For example, the lending of SEC-regulated securities like stocks is not regulated by the SEC, it is regulated by FINRA.
Cryptocurrencies are not generally securities, though some may be. To the extent this isn’t limited to securities, it would not be regulated by FINRA.
> their expectation was that the accounts would regulated by another entity, presumably the FDIC or FINRA.
FDIC doesn’t insure, and therefore regulate, cryptocurrency accounts. I’m reasonably certain Coinbase is aware of this fact. [0]
> The whole situation smells of a turf war between regulatory agencies,
Which other regulatory agency is asserting authority?
[0] https://help.coinbase.com/en/coinbase/other-topics/legal-pol....
Neither the SEC nor FINRA has stated anything public about this at the moment, but I'm willing to bet FINRA will go to bat for this.
If the SEC says no, FINRA can't say yes, because (to a first approximation) that's their boss.
And just from first principles, I'm not sure that FINRA, an organization largely dominated by traditional broker-dealers would be willing to go to bat for a weirdo newcomer. If they aren't doing the basics of building relationships with the SEC, is Coinbase building relationships with the other companies necessary to get FINRA to go to bat for them? But again, not sure about this, just a bit skeptical.
Coinbase certainly started out with the rogue "Can't touch me, it's crypto" bullshittery, but over the past 6 years they have been one of two exchanges (the other being Gemini) which have actually taken regulatory approval and collaboration seriously. Maybe the SEC's fines and handslaps have made them fear the alternative, who knows. Whether that means that they can really have any influence over FINRA is yet to be seen.
The whole situation smells of a turf war between regulatory agencies, which is entirely in character for the SEC. They've been doing the same shit for years with the CFTC. You're no longer allowed to trade forex using the same account that you trade stocks with...not because the SEC regulates forex, but because they want to regulate forex, and are trying to strongarm the CFTC into ceding it's jurisdiction by crippling the forex market. This is plainly another turf war play, trying to grab territory that is far more cleanly regulated by FINRA.