master-slave vs masterless architecture

As per Riak's doc

"Most relational databases leverage a master/slave architecture to replicate data. ...

Conversely, Riak uses a masterless system with no single point of failure, meaning any node can serve read or write requests."

What are the advantages of using masterless instead of master-slave?

We can simulate the same masterless behavior in master-slave architecture, where at any time when master is down any slave nodes can become master.

I'm not able to understand the advantages of 1 over another.

I don't know where to ask, Please provide me link where I can ask the que, if this is not correct place to ask.