Well I don't think you can count Rousey an Olympic level Judoka And yes there are always exceptions, but generally European fighters don't have that history of fighting on the ground through college/high school/university that US fighters do. Whenever they end up on their back they tend to stay there until the bell.
I think I can count Rousey. The UK has a vibrant Judo scene and Europe even more so, so if Judo can cancel out the lack of wrestling, then there's no real issue is there?
I can't find a decent video of the Kennedy fight, so who was the ref who gave Romero extra time? Ignoring the rules that if you can't answer the bell you deserve to lose, if he needed extra time to recover then the fight clearly needs to be stopped. To me, that's a ref failing in his primary duty to protect fighter safety.
And after some more reading I gather he wasn't actually hurt so I withdraw the point about fighter safety. Although I do think Big John gets a lot more credit than he deserves these days. On another note, browsing Sherdog someone has suggested a Mcgregor - Edgar fight and I for one am interested in the sound of it.