Because then your browser would itself have to be a torrent client.
The way torrents download is fundamentally different from how a standard http download works, which is why they have a specialist implementation. Browsers dont want to bother bringing a whole load of new code and associated bugs into the browser to do a job which isn’t really connected with the browser’s main responsibility, which is browsing the web.
Just because torrents come from the web shouldn’t make it the browser’s responsibility to deal with them.
You just reminded me there actually was a browser called Torch that could download torrents like a normal download. It was basically just Chrome with a built-in torrent client.
I remember trying it out when it first came out in 2012. It never caught on and looks like the last release was in 2020.
Opera had torrent support at the time I stopped using it, I never heard they had discontinued that feature but I’m assuming they did, both because it probably would have been mentioned in this comment chain already and also because making that decision should have been inevitable. I never used bittorrent before joining oink, I think I remember on joining thinking I would just use opera and then installing utorrent after finding out client whitelisting was a thing. Maybe I was already on oink when opera added the feature and I thought I’d try it because I was already using opera. Maybe this is all a fever dream, who can really say.
