Because using a browser on a TV is a super awkward experience? If it's not an app optimized for TV then it's better it's not there in the first place.
Puffin Browser isn't bad on Android TV. I don't use a browser very much on my TV but, when I do, Puffin has been more than up to the task.
It's not included in any Android TV device.
You can side load it yourself, works okay.
I think Google wants to limit the capabilities so we will only use the apps they want. Another plus is that you can run it on cheap hardware and get more people looking at your huge ads.
This is why I stay on my Android tv box. I can install any browser available . I use Open Browser app for video pages and DuckDuckGo browser for everything else
Sony Android TV devices do include a browser, pre-installed.
Google don't port Chrome, but there is very little use for a browser in practice anyway and I imagine it's just because they don't want to bother maintaining a UI.
Somewhere some google Android TV developer is sitting there thinking "you're doing it wrong"
Use JioPagesTV browser. Available on Android tv play store. Completely optimized and highly usable for Android tv. It's a chromium browser, so almost all features of chrome available in it.