The importance of having periodic backups is a given in Database life. There are different flavors: binary ones (Percona XtraBackup), binlog backups, disk snapshots (lvm, ebs, etc) and the classic ones: logical backups, the ones that you can take with tools like mysqldump, mydumper, or mysqlpump. Each of them with a specific purpose, MTTRs, retention policies, etc.
Another given is the fact that taking backups can be a very slow task as soon as your datadir grows: more data stored, more data to read and backup. But also, another fact is that not only does data grow but also the amount of MySQL instances available in your environment increases (usually). So, why not take advantage of more MySQL instances to take logical backups in an attempt to make this operation faster?
Distributed Backups (or Using all the Slaves Available)