I would agree with this statement. In my discipline Entrepreneurship, the leading journals are all US. The outcome of this is a preference for particular research methodologies and in some papers I have read the exclusion of non-US literature from theory construction.
US dominated editorial boards must have quite a few implications, including the ones you have mentioned. It forms a US centric view of knowledge that has implications for what is accepted on occasions. It is a big issue in research and publishing that seems too controversial to discuss at conferences. Getting the benefit of the doubt with submissions can be rare for academics outside of the US.
We in Africa and least developing countries, it is not surprising to us. A look at the budget and funding for research in Africa and LDC when placed side by side with the United States, it is very clear that the United States journals/editors will naturally be dominant in the advancement of the frontiers of knowledge in most discipline. The implication of this trend is that the United States businesses benefited more from the outcome of most of the researches.
It certainly is true in Canada and does have significant implications. We often rely on US literature that seems relevant and yet implies a very distinct set of variables. In my field for example, Inclusion, we are quick to cite American studies when it should really be accepted at this stage that the US context is different for innumerable reasons. This limits local creativity when scholars are quick to look to US solutions which might be quite incompatible with the on terrain context. We can only predict that this will become more marked as the US takes its current peculiar path.