The US are currently dominant, and have been for this quad and a good portion of the last. Before then, they were steadily rising and certainly had a healthy dose of victories, but couldn't have been called outright dominant. The code has been almost universally blamed for this. A key point to remember is that US dominance is bad, while USSR dominance for essentially decades was good.
No. Bias shouldn't come into this. Dominance is bad full stop. Aside from anything else, it is freaking boring when gold will be won by 7+ points in a globally attended team final. The top 4 is no more in the sense of close competition. There's 1, and then 3-all of whom seem to deteriorate year on year despite the addition of new seniors. And then the rest, countries like GB, Germany and Italy who can't quite get up there to the same level.
Because of the code and the demand for difficulty? The code suits the US..now. It was not made for them, and certainly FIG themselves are not relishing the fact that it IS suiting them so well. Bruno and Nellie have both condemned this reality. The US adapted to the code. The level of difficulty increased steadily year on year. We have now gotten to the point where H skills and amanars are nothing out of the ordinary and the gymnast with the most difficulty of this quad, Simone Biles, is throwing far more than her compatriots of previous quads, Jordyn Wieber and Shawn Johnson. The reason why they've been able to do this is because of the resources, coaching and training that they have. Many of the coaches that fled from the east on the collapse of communism are ensconced in US gyms. This exodus, predictably, has had a major knock-on effect on the quality of coaching in their former countries. Much bigger salaries and a much greater quality of life is a huge draw of course.
Rather than a centralised state-funded programme, the US operates privately funded gyms on a grand scale. In that way, the success of individual gymnasts and the National team is not impeded by economic downturns. Programmes like that of the Ukraine are sad former shadows of themselves- even in the last 10 years. Money is not an object for the US, although of course the gymnasts and gyms also benefit from the National team training camps, a big part in the success story since 2000. The girls enjoy the best of both worlds- their coaches learn from top elite training staff. It's the little things too-they are able to have flexible arrangements as regards schooling, with several being home schooled or supplementing with online classes. This is not an option in other countries with more rigid educational structures with the direct effect of less training time or the altogether worse-education being willfully ignored. A few years ago, most of the gymnasts sitting the BAC that year in Romania failed it.
In short, the US are so good right now because they have mastered the code...because they have the resources, coaching, back-up, facilities.... everything in place to do so. And none of the other powers do. That is not the fault of the US. It's a direct result of keeping to the old ways when they no longer suit. People are no longer enrolling their children in gymnastics in countries like China and Russia. The private, individual system works in tandem with a national team set-up, and clearly works brilliantly. Countries like GB have come on quite a bit with this (although clearly have a long way to go) whereas adherents of the old ways are stagnating and/or deteriorating.
The difference in resources is the problem. NOT the code. The code is inherently flawed and could do with a complete overhaul, but the US would adapt to that too. They'd be able to handle anything the FIG can throw at them, and that's the key to their success.
Last year, we witnessed Mykayla Skinner being bumped to 4th place in the worlds floor final, after performing her incredibly difficult routine to the best of her ability. The bump-er was the last performer, Aliya Mustafina, who had only 3 passes, but much less deductions. This is what the code can be made to do, reward execution at the expense of messy difficulty. There needs to be more scope to do this within the scoring. If they added back in RSV which I will keep advocating for, then gymnasts who perform difficulty effortlessly and cleanly such as Simone Biles would still be rewarded and the motivation to chuck a skill would be much diminished. It is false to assume that there is only one perpetrator of this - girls of many countries are performing skills they have no right to do. With the very odd exception, the US believes strongly in performing only that which you are capable of, and perceptions of the contrary are quite unfair.
Blaming the code itself is too easy. There are many reasons why WAG looks so ridiculously top-heavy, and the code is only a symptom, not the cause.
In other news, I have a shiny new laptop :D Use of the internet is no longer an insurmountable struggle, hurray!