* Possibly Sybil attacks get worse or harder to detect, because attackers can convincing simulate being a bunch of regular users with a browser
* Possibly mitigating malicious nodes gets harder, because people can create lots of super-ephemeral nodes that fail to forward traffic, but there's no way to notice this in time to protect other users
* Users could be very angry about relaying exit traffic without expecting it, especially if they got in legal trouble as a result (when EFF ran a campaign to encourage people to run Tor nodes, we discouraged people from running exit nodes in their homes)
https://2019.www.torproject.org/docs/faq.html.en#EverybodyAR...
Some other problems:
* Possibly Sybil attacks get worse or harder to detect, because attackers can convincing simulate being a bunch of regular users with a browser
* Possibly mitigating malicious nodes gets harder, because people can create lots of super-ephemeral nodes that fail to forward traffic, but there's no way to notice this in time to protect other users
* Users could be very angry about relaying exit traffic without expecting it, especially if they got in legal trouble as a result (when EFF ran a campaign to encourage people to run Tor nodes, we discouraged people from running exit nodes in their homes)