I would guess Fred's not saying boatloads of vessels can't go out in oceans... but rather most are not built to do multiple intentional Atlantic or Pacific (or whatever) passages.
Our boat could also do OK in seas you describe -- I don't wannq be there at the time
-- and there's an online blog out there where some folks actually did take our model to St. Thomas, got really beat up en route, and the boat did fine. We also routinely go outside when the opportunity presents itself... but I wouldn't describe our boat as ocean-going in the Nordhavn (for example) sense. Not just about fuel capacity, but also design: our windows are too big, the interior is too open with too much (self-induced) loose furniture, etc.
My own informal approach might be to ask myself if I would be "this" (candidate) boat for a trip from the Chesapeake to Barcelona (or some such)? The boat we have now? Not so much...
OTOH, I wouldn't really hesitate to cross from FL to the islands...
That's just my interpretation, though; FF can answer for himself.
-Chris