i think it saves old conf files in an rpm cache under var somewhere o r sometimes in the same directory if directory remains after remove, so no there is now purge command, but the old conf files are saved and you can delete them if you want to.

find / -print | egrep "rpmnew$|rpmsave$"

you can pipe this to rm or whatever or total up the size and see if it is really worth worrying about

other than that, hopefully it is coming for dependencies removal

https://features.opensuse.org/300758

supposedly mandriva has something similar now.