The author's addressing the situation in the US in particular but it's just as applicable to the UK and Europe, the latter being singled out in the article.

Europe needs to do its part as well, blocking more mergers, especially those like Bayer’s recent acquisition of Monsanto that threaten to put entire global industries in just a few hands.

This section in particular is the crux of the issue.

There is a direct link between concentration and the distortion of democratic process. As any undergraduate political science major could tell you, the more concentrated an industry — the fewer members it has — the easier it is to cooperate to achieve its political goals. A group like the middle class is hopelessly disorganized and has limited influence in Congress. But concentrated industries, like the pharmaceutical industry, find it easy to organize to take from the public for their own benefit. Consider the law preventing Medicare from negotiating for lower drug prices: That particular lobbying project cost the industry more than $100 million — but it returns some $15 billion a year in higher payments for its products.