It should, but in practice it doesn't. I've had torrents that I left sitting for weeks not being able to complete, until I added a list of trackers to them and found some seeders with 100% of the torrent.
Just because not everyone is using DHT does not mean that it doesnt solve the issue.
Same here.
BT only worked for new popular stuff.
I've yet to find something that's truly unavailable. Sometimes it takes a few different searches on different sites but I've always found the obscure Linux distros I've been looking for.