i assume that it also makes it harder for miners to slip bad stuff in as well, because they have to
a) win a block
b) coordinate with bad actors and have a file ready when they do win a block
c) leaves a fat trail for legal
versus if we are all just relaying stuff around, and Oops a miner wins a block and accidentally stuffs a bunch of bad stuff in the time chain it's going to happen frequently and via people who are unwitting participants.