> You achieve reliability with erasure codes, not with more replication

If nodes are not trusted then replication has to play a major roll.

It doesn't matter how you mix up the data. You still have to store it somewhere and if that somewhere is a random untrusted stranger you will need to copy your data to a lot of random untrusted strangers in order to have kind of reliability.

It does play a major role, in fact I think not everyone figured this thing out yet, some not even taking into account countries as risky availability zones. But the storage space overhead for redundancy is at worst 2x, which could eventually be reduced by a lot.

you could achieve some trust through a reputation system. the longer you've been reliable the more reliable you are.