Much of the scholarly debate around platform regulation is
outcome-focused, concerning rules and norms that should govern platform behavior, rather
than focusing on questions of policy processes. However, the question of politics underlying
the development of these rules is essential to understanding how and why particular forms of
oversight have developed in response to the growing scope of platform capitalism. To address
this gap, this paper provides a preliminary account of why competition policy has emerged as
a prominent governance mechanism for platform oversight, which privileges stronger antitrust
enforcement and economic regulation and has resulted in antitrust lawsuits against and
investigations into major tech companies like Google and Facebook. With the US as a case
study, I examine a series of 2017-2020 policy debates about oversight of digital platform
markets, exploring how the boundaries of competition policy are discursively contested and
negotiated in these debates by stakeholders ranging from policy experts to regulators to
public interest groups. I argue that these policy debates, driven by a burgeoning
antimonopoly movement, produced a set of policy ideas vis-à-vis platform oversight that
coalesced around a governance paradigm rooted in competition policy. However, the framework
ultimately ultimately prioritizes optimizing competition in digital platform markets above
other goals, like data regulation. Consequently, it came up short in providing a policy
answer to the expansive forces driving platform capitalism. I theorize these blind spots as
partly attributable to the dominance and insularity of the competition policy framework as a
foundation for governing platform sectors.