It's true that BEP-46 'Mutable Torrents' exists now, but trustless DHTs like Bittorrent Mainline are vulnerable to Sybil attacks [1][2], which is conceptually similar to a Blockchain 50+% attack to where a malicious party can control a large amount of nodes and propagate lies. You want to involve some incentive scheme to counteract this [3].
It will not help to eliminate attacks by using point 3 as you are still on the bitcoin network on which 50%+ attack can be made.
Using mutable torrents you are attaching public key to .torrent file and then just signing any changes with your private key. It's even better than bitcoin and without flaws of bitcoin which i mentioned.
You need to get information about content/website that you want to access somewhere, don't you ? So with this information you can get also sha256 of the public key that is attached to.torrent.
They're not quite the same in computational effort. To attain 50+% on Bitcoin you have to actually solve proofs-of-work on the blockchain. To execute a Sybil against Mainline you just have to show up.
Of course it is harder which doesn't change at all what i wrote = it's possible. Then i explained how to make sybil against your content impossible. Your both points in context of my previous reply are invalid.
[1] https://en.wikipedia.org/wiki/Sybil_attack [2] http://ieeexplore.ieee.org/document/6503215/ [3] https://news.ycombinator.com/item?id=10029851