Yes, it's an add-on and not built into Chrome... and yes you have to know about it to install it in the first place. I'm not exactly sure that's a problem though - if you are technical enough to navigate through settings menus in your browser, understand what the settings mean and toggle options (presumable to enable some built-in version of uBlock Origin), then you clearly have the capability to install the add-on.
Browsers filtering "known trackers" is a very quick slide into "known malware", "known spammers", "known foreign propaganda", "known conspiracy theories", "known fake news", and more.
It's the exact path that social media and other online platforms took, and guess what? The same companies build browsers.
With that, I also agree that Google couldn't be trusted to editorialize.
Related: I don't understand why people choose to work for Google