Yeah, but you can deal with that, if you know what you're doing. If you use Whonix, or roll your own Tor gateway, leaks around Tor aren't an issue. UDP is the hardest thing to deal with. I mean, with proper Tor/userland isolation, leaks don't happen. So all UDP just gets dropped. If you want UDP, you need to use OnionCat or tunnel a VPN through Tor.
ZeroNet doesn't use the torrent protocol for distributing file. It uses its own TCP service for that so avoids the issues of tunnelling UDP over TCP. Its use of "bittorrent" technology is limited to the protocol for mapping ZeroNet site addresses to IP/Onion addresses.
So will ZeroNet map addresses to immanent Tor onion addresses, which are much longer? That change will screw OnionCat, sadly enough.
Also, I wonder if MPTCP would play nice with ZeroNet. MPTCP works very well With OnionCat. I could create TCP streams with hundreds of subflows over all possible combinations of multiple OnionCat addresses.
That's a privacy concern, not a load problem.