There already are automatic backups. From Manage Domains or MySQL, there’s a Restore button on the far right for each domain or database. Give it a look to see how far back the backups go. Mine show a couple of weeks for domains, and about a week for databases.
However…if something at Dreamhost self destructs, I wouldn’t count on their automatic backups to be reliable. They’re handy if you mess something up, but the best way to backup your data is to do it yourself. For some tips, go to https://help.dreamhost.com/hc/en-us and search for “backups”
For myself, I use mysqldump and rsync to keep a local copy of my websites. TimeMachine is part of my local backup regimen that helps keep multiple copies of my site backups. Plus mirroring (via SuperDuper) to an external drive I keep offsite.
Since most of my sites are using WordPress, I use UpdraftPlus to backup my data to DreamObjects (only costs a buck a month) or to Dropbox.