keybase.io offers a nice way of getting someone else's PGP key and other encrypted keys.
However it's a centralized service so it can still relate people to each others. It would be more preferable to share the key in person and not over the internet.
Someone could anticipate that the relation between people sharing keys on that specific webiste can turn out to be dangerous.
On the other hand, no one can foresee that on a random website an individual that visited a certain day, and only this day, could communicate with another stranger something dangerous. After the fact no one can retrace what happened because no one was waiting for it to happen at this place and at this moment.