Conflict of interests. We were told these things by the very same people who have an interest to rigging an election :-)

at some point, this problem boils down to something like trusting trust and I think that the answer might be similar to how stage0 in compilers work in that smaller stages which can be easily audited combine/compile together to form larger stages. (Not sure if this allegory fits at the moment but I do feel like decentralization can definitely help in these cases which is my point but these same people who told that it wasn't possible aren't looking for/actively hindering any prospects of decentralization due to once again, conflict of interests)