Should Facebook, Google shield users from the legal consequences of posting illegal posts? If we were using e.g. Ted Nelson's Xanadu (instead of the WWW) every

Should Facebook, Google shield users from the legal consequences of posting illegal posts? If we were using e.g. Ted Nelson's Xanadu (instead of the WWW) every post and link would have provenance information and it would be technologically feasible to make the original source of a given piece of illegal content liable for the legal consequences of publishing it, as well as each and every person/entity that promulgated it across the network. As it is now, these platforms omit or delete provenance information, making it technically impossible to moderate at scale.