Besides, techniques for identifying fakes is likely to lag closely behind the techniques for producing them.
The first time we talked about "DeepFakes", someone I know pointed out that there is nothing inherently new in this issue. Media has been faked to manipulate the truth as long as there has been media.
Wether you trust the medium, a person, or a blockchain, trust is only as good as the information you base it upon – and there's always ways to circumvent it, or otherwise deceive you.
Also: There are some pretty big privacy issues (from what I understand) with what you describe.