If an ISP fully embraced the Net Neutrality repeal and started blocking video content, and someone posted on HN that ISPs were "blocking them from building a streaming service", no one would be complaining that, "technically you can build it, you just can't reach any of your customers." Everyone on HN would understand that part of building a service is the having the ability to reach customers.
In the same way, part of building a web browser is having the ability to render web content. If Google can block your custom browser from rendering content, then for all practical purposes they are blocking your ability to build a browser.