Registry never made much sense on the local system: just use the filesystem. I assume there was once a plan to use it in a networked fashion. But Active Directory replaced it for that purpose.
Dconf complements it: https://wiki.gnome.org/Projects/dconf and dconf-editor is even similar to regedit.
For system settings... that is a bit more complicated.
There is a standard and it's minimal:
- config files are text files - # indicates a comment
Why standardize further when the types of programs that require config files run an extremely wide gamut? Types of programs can be as diverse as web servers, graphic editors, kernel modules, networking programs, etc. Each are vastly different. I don't need to wait for, worry about, or try to install an updated registry processor that knows about new object types. Better to build it into the program or rely on a library. Why change the entire system of configuration storage just for one new type of program?
And text files are awesome for another reason: With the ability to comment config files you can understand any format - as well as include notes and conveniently have documentation where you need it.
Also: You can't use git or other versioning to backup your registry keys and rollback to previous versions.