Oh boy, antitrust is my pet political issue so I apologize for my inability to maintain impartiality (and wall of text) in advance. I would say that America has gone through this debate already and perhaps we should look to our history. Take this:
The tremendous and highly complex industrial development which went on with ever accelerated rapidity during the latter half of the nineteenth century brings us face to face, at the beginning of the twentieth, with very serious social problems. The old laws, and the old customs which had almost the binding force of law, were once quite sufficient to regulate the accumulation and distribution of wealth. Since the industrial changes which have so enormously increased the productive power of mankind, they are no longer sufficient.
The growth of cities has gone on beyond comparison faster than the growth of the country, and the upbuilding of the great industrial centers has meant a startling increase, not merely in the aggregate of wealth, but in the number of very large individual, and especially of very large corporate, fortunes. The creation of these great corporate fortunes has not been due to the tariff nor to any other governmental action, but to natural causes in the business world, operating in other countries as they operate in our own.
The process has aroused much antagonism, a great part of which is wholly without warrant. It is not true that as the rich have grown richer the poor have grown poorer. On the contrary, never before has the average man, the wage-worker, the farmer, the small trader, been so well off as in this country and at the present time. There have been abuses connected with the accumulation of wealth; yet it remains true that a fortune accumulated in legitimate business can be accumulated by the person specially benefited only on condition of conferring immense incidental benefits upon others. Successful enterprise, of the type which benefits all mankind, can only exist if the conditions are such as to offer great prizes as the rewards of success.
The captains of industry who have driven the railway systems across this continent, who have built up our commerce, who have developed our manufactures, have on the whole done great good to our people. Without them the material development of which we are so justly proud could never have taken place. Moreover, we should recognize the immense importance of this material development of leaving as unhampered as is compatible with the public good the strong and forceful men upon whom the success of business operations inevitably rests. The slightest study of business conditions will satisfy anyone capable of forming a judgment that the personal equation is the most important factor in a business operation; that the business ability of the man at the head of any business concern, big or little, is usually the factor which fixes the gulf between striking success and hopeless failure.
Now this is Teddy Roosevelt in 1901 but tell me that doesn't sound an awful lot like today! And this is the president known as the trustbuster, speaking in general favor of business. I won't spell out how he reconciles this with his general opinion in favor of antitrust regulation because hopefully that hook can get you to read the rest of that speech here.[0] And here[1] is a speech by John Sherman. These are the men who convinced our country of the importance of antitrust over 100 years ago and much rings true today. Perhaps we should consider these arguments first so we can at least avoid retreading old ground.
And to plug one article I love, check out Bloom and Bust by Philip Longman[2]. He uses this quote from Woodrow Wilson in 1912:
Which do you want? Do you want to live in a town patronized by some great combination of capitalists who pick it out as a suitable place to plant their industry and draw you into their employment? Or do you want to see your sons and your brothers and your husbands build up business for themselves under the protection of laws which make it impossible for any giant, however big, to crush them and put them out of business, so that they can match their wits here, in the midst of a free country with any captain of industry or merchant of finance … anywhere in the world?
[0] http://www.emersonkent.com/speeches/controlling_the_trusts.h...
[1] https://babel.hathitrust.org/cgi/pt?id=wu.89098552482;view=1...
[2] http://washingtonmonthly.com/magazine/novdec-2015/bloom-and-...