YouTube and inspired sites technically offers more than just video watching. Torrenting accomplishes the file service, but it doesn't accomplish much else.
i.e cataloging (displays videos as a catalog of thumbnails with title and description)
search (Google considering, its a robust search engine)
playback features (e.g playlists)
social features (commenting, favorites, user ratings, sharing playlists)
You can replicate #1 with an online image gallery and magnet links for your own personal website, but attaining notoriety and the consistent seeds to support larger uploads without a major hub is the big challenge. This is often combined with #2 in the case of YouTube.
#2 while you technically can put up your videos on a torrent tracker and be included in the torrent search there. They don't often have the website laid out for videos like above. Plus you would be competing with pirated TV shows, movies, and illicitly available high production value content for viewership.
#3 is easily done with a video player, but it has to be specific video players that supports incomplete files.
#4 is not very available. You can technically use Twitter or GNUSocial to get across something similar without the tailored specificity to videos.
Consider above. The barriers of your viewership are:
+ knowing about you in the first place and liking your content enough to have a different use case to access said content
+ being able to find your videos
+ having the right fully featured system media player
If your viewership cares about automated feedback systems,
+ following you on social media and not on your blocklist
So to speak, these webapps are not alternatives to torrents, they are essentially GUI's and front ends that do not have a software alternative/competitor.