I'm afraid I must disagree.
They have an effective monopoly on the micro advertising and CPC market in the same way as Microsoft was found to have one in the OS sector.
Were there other OS choices when Microsoft got slapped in court (as they did yet again in Europe)? Yes, of course.
Are there options both major and minor in the AdWords niche? Yes.
Is there any doubt that AdWords occupies the vast majority of the transaction space? Me thinks not.
I am no fan of regulation. But the time is coming when Google may find itself looking at an experience with State AGs, Congress and European regulators not unlike that faced by Microsoft.
Could not happen to a bunch of more arrogant people in my experience.