Earlier quoted context omitted.
One of the tough things about a party-controlled, self-hosted e-signature is that it becomes easier to repudiate because a party to the contract has custody of the platform. The non-custodial party can claim they never signed, and when the custodial party produces evidence of IP address and timestamp, the non-custodial party may have a credible argument that they are faked and the person asserting those authenticated…
If only someone would invent a public nonrepudiatable ledger.
The fundamental challenge here is that there's no way to tell, based on a the signature alone, which signatures are "valid" and which are "forged"; they're not cryptographic signatures. And getting cryptographic signatures for lay people is apparently too hard to do, outside of Estonia's digital citizenship initiatives.
It might be neat if the big guys agreed on an OIDC extension that let you piggyback text to be affirmed by the user. Cryptographic proof that jane.doe@gmail.com saw text with hash H at time T and chose "Accept".