All this will do is encourage the proliferation of innumerable bespoke blockchains, created by parties interested in stamping legitimacy on illegitimate content

All this will do is encourage the proliferation of innumerable bespoke blockchains, created by parties interested in stamping legitimacy on illegitimate content. Each of these blockchains will be presented as equivalent to "the blockchain" with respect to being trustworthy proofs of original untampered content timestamps.