Why is there no support for a webrowser on Apple TV?

As this is a user-to-user community, no-one here can tell you why Apple made that decision.

From a personal perspective, general browsing is much more comfortable and readable on a computer or mobile device. Browser support is often better when you can install/use the latest version of Safari, Chrome, or Firefox. If needed, the browser window can be send to Apple TV through AirPlay screen mirroring. Similarly, compatible web video can be streamed to Apple TV from the Safari browser using in-app AirPlay.

You can leave feedback comments and suggestions at: Feedback - Apple TV - Apple.

likely because it's a horrible experience, my xbox have a browser it's a pain to use, plus browsers have extensions and plugins and the likes which would not be a thing on the appletv so people would feel it an inferior experiences compared to on a computer, you can airplay the browser from a computer, ipad or iphone to the tv by using the appletv

Feed it back here Feedback - Apple TV - Apple

we can ask why Apple does something or does not to something else. We would be here all day :-) why not have Apple news app on Apple TV or Apple Books app on Apple TV etc. etc. Your best bet would be to use airplay like the prior poster as advised.