Online advertising has existed for over 25 years. [1] Online ad brokers (i.e., competitors with Google) have existed for nearly 20 years. It is incredibly disingenuous of you to pretend as if Google is in any way "forced" to play both gatekeeper and ad broker, like no-one else is trying to compete in that space. Developing Chrome was a deliberate choice by Google to position themselves to own the means by which users consume ads, search (ads), and video (ads).
Internet is young. There will be some regulations and standards, eventually.