they are using a tech I'm not entirely familiar with.   but block chain is not like sour dough.    block chains power is that it keeps a record by having blocks of data..  and these blocks have a verification number generated from the block that is then put into the next block in the chain.  If anything is altered in the pervious block that verification number won't match, breaking the chain because each block depends on the last... so you can't alter part of the block chain without breaking it. so the idea I think for this server is that the blocks would be decentralized and located on folks that chose to be servers.   because the data can't be altered who hosts isn't important. I'm no expert on block chain... but I know enough to understand it.